You won’t believe there’s no cream or cheese in this rich, low-carb, gluten-free spaghetti squash lasagna. Fresh basil gives it a fresh, peppery zing.
Right before I went vegan, I made the best lasagna I had ever tasted. It was called Pesto Lasagna, and it contained eggs and three kinds of cheese. It was so rich and creamy that I never tried to recreate it as a vegan because a cheeseless, low-fat version seemed impossible.
I’m not usually one to shy away from tackling the impossible, but I didn’t want to tamper with the memory of a meal that had grown to mythic–and probably unrealistic–proportions over the years. But this week I decided not only to take on the pesto lasagna of my vegetarian days but also to do something I never would have dreamed of doing back then: substitute the noodles with spaghetti squash for a lighter, gluten-free, but still rich and creamy lasagna. And I’m so glad I did!
But before there was success, there was failure. My first attempt never really got past the spaghetti squash stage. I had bought a small, 2-pound spaghetti squash at the farmers’ market, and I roasted it, as I’ve done in the past. But when I cut it open, the insides were a wet, clumpy mess, not the individual strands of gold “spaghetti” I was expecting. I couldn’t even separate the seeds from the flesh because it was all one sodden pile of mush. I must have cooked it too long for its size, but that’s the problem with cooking a spaghetti squash whole–you can’t check it to determine when it’s done.
For my next attempt, I decided to cut the squash in half before cooking so that I could check its doneness. I went down to the grocery store and bought a medium-sized squash, a little over 3 pounds. I didn’t want to wait the hour it could take to roast the squash, so I decided as a short-cut to pressure cook it instead.
I fitted my electric pressure cooker with a gadget I’d just bought, a silicone steamer basket, added a cup of water and the two halves of the squash, and then set the timer on high for 8 minutes. I figured that if it needed more time, I could always add another minute, but when I checked it, the squash was perfectly cooked, tender enough that I could scrape out the golden strands but not turning to mush.
The squash turned out perfectly and so did the lasagna. My husband raved at how good it was and told me that, frankly, he hadn’t been optimistic about spaghetti squash instead of lasagna noodles. But we both loved the creaminess of the sauce and filling which contrasted with the slight crunch of the “noodles.” And the fresh basil gave it a fresh, peppery zing. It was a complicated dish to make on a weeknight, but I’ll definitely make it again.
If you’re looking for an easy, basic lasagna with actual lasagna noodles, be sure to try my Easy Spinach and Mushroom Lasagna!
Spaghetti Squash Pesto Lasagna
- 1 medium spaghetti squash about 3 pounds
- 8 ounces sliced mushrooms
- 1 clove garlic minced
- 1 1/2 cups low-fat spaghetti sauce packaged or homemade
- 1 cup spinach optional
- salt and freshly ground black pepper to taste
- 2 cloves garlic peeled
- 1 14-ounce package extra-firm tofu not silken
- 1 cup fresh basil packed
- 2 tablespoons nutritional yeast
- 1 teaspoon salt if you use
- 1/8 teaspoon cayenne pepper optional
- 1 cup plain sugar-free non-dairy milk
- 1/4 cup nutritional yeast
- 1/4 cup raw cashews about 1 ounce (optional, but very good)
- 2 tablespoons potato starch or cornstarch
- 1 tablespoon lemon juice
- 1/2–3/4 teaspoon salt if you use
- 1/2 teaspoon dry mustard
- Cook the spaghetti squash. You can bake it, microwave it, or do as I did and pressure cook it. To pressure cook, cut the squash in half and scoop out the seeds. Place a steamer basket in your pressure cooker, add 1 cup of water, and place the squash halves in the basket. Seal pressure cooker and cook at high pressure for 8 minutes. Release pressure, uncover, and allow the squash to cool until you can handle it comfortably.
- Using a fork, scrape out the strands of “spaghetti.” It may take a little effort and going “against the grain.” Put the squash strands into a colander set over a large bowl and set aside. (You can cook the spaghetti squash ahead of time as long as you drain it well before using.)
- Heat a medium-sized sauce pan. Add the mushrooms and 1 clove chopped garlic, along with 1 tablespoon of water. Stir and cover tightly. Cook, stirring every 60 seconds, until the mushrooms soften and exude their juices, about 3 minutes. Uncover and cook until most of the liquid evaporates. Season lightly with salt and pepper, if you like, and set aside.
- Make the filling: Start your food processor and drop in the 2 cloves of peeled garlic. Process until finely chopped. Add the remaining filling ingredients and process until smooth, stopping to scrape down the sides of the bowl if necessary. Set aside.
- Make the cheese sauce: Place all sauce ingredients into a blender and blend until completely smooth.
Assemble the Lasagna
- Preheat oven to 375F. Lightly oil a 2 1/2 to 3 quart oblong casserole dish. (Mine is 9.5 X 6.5 X 3 inches deep.) If you don't want to use oil, try lining the dish with parchment paper.
- Spoon about 1/4 cup of the spaghetti sauce into the bottom of the dish, just enough to coat the bottom. Spread half of the spaghetti squash over the sauce, and sprinkle with salt and pepper if you like. Drop the filling over the squash by large spoonfuls and then spread it out evenly. Arrange the mushrooms over the filling, followed by the spinach, if you’re using it. Pour half of the cheese sauce over the spinach and mushrooms. Add the remaining squash, smoothing it into an even layer. Pour the remaining spaghetti sauce over the top.
- Bake for 15 minutes. Then carefully, starting in the center of the pan, pour the remaining cheese sauce over the top, being careful not to splash the sauce onto the hot pan. Return to the oven and cook until the lasagna is bubbling all around the edges, about 30-40 more minutes. Remove from oven and allow to stand for at least 15 minutes–the sauce will thicken and the lasagna will be less watery the longer it stands. Serve warm.
Nutritional info is approximate.
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JessieNovember 19, 2013 at 4:42 pm
I always love your recipes, but you’ve outdone your self with this one! A-amazing, I could have this every night, and it doesn’t give me that overfull feeling lasagna noodles give. Just wonderful <3
JillNovember 20, 2013 at 12:54 pm
I’ve been cooking your recipes for a few years now and this one is at the top of my list! It was fantastic. I almost didn’t make it because I do NOT like soggy anything, but I found that gently pressing the squash between some paper towels got rid of all the liquid. It came out perfect!
Michele MarieJanuary 17, 2014 at 5:41 pm
great idea to press the squash! I will be doing that!
rockNovember 24, 2013 at 9:14 am
ok. so this was amazing. im a new (8 month old) vegan and i also a health nut. looking for healthy but tasty vegan recipes. i and everyone in the family LOVED this. thx
CarolinaNovember 27, 2013 at 4:00 pm
I made this last week and it was amazing.
My husband loved it and it was great as left overs the next day! I think next time I might add more basil.
Jessie WilkinsonDecember 1, 2013 at 2:33 pm
I made this last week and it was so amazing! This week I didn’t have any tofu and replaced it with polenta and it was still delicious!
HeatherJanuary 8, 2017 at 4:13 pm
I have no experience with cooking polenta. How do you prepare it for this recipe?
CynthiaSeptember 17, 2021 at 5:24 am
This look amazing, any ideas on how to make it without tofu? (Partner has soy intolerance)
Susan VoisinSeptember 17, 2021 at 7:34 am
You might be able to substitute white beans for the tofu.
JustinaDecember 5, 2013 at 12:53 pm
I just made this and WOW, it is so yummy!! The tofu-basil filling really tastes like the ricotta filling in lasagna. Delicious!
JuanitaDecember 14, 2013 at 12:09 am
This was delicious even with my nightshade-free pasta sauce substitute! I have my own recipe for a pumpkin sauce that I’ve been using since I haven’t been able to eat nightshades for just over a year.
Susan VoisinDecember 14, 2013 at 1:10 pm
I’m so glad you enjoyed it!
Stephanie DeesDecember 28, 2013 at 4:14 pm
LOVED this. I’ve been an avid reader (stalker?) for years and don’t know if I’ve ever commented on a recipe before, but I just had to say thank you for this gem. My husband and 3 year old son gobbled it up too, and it got even better after one or two days in the fridge. Also, I’ve always failed at spaghetti squash in the past, your pressure cooker idea worked perfectly! Thanks again for all your great recipes and keeping me inspired in the kitchen!
MichelleJanuary 16, 2014 at 6:59 pm
I made this tonight and it is a total winner! This is going to be a regular part of my recipes for sure!
Michele MarieJanuary 17, 2014 at 5:39 pm
Perfect! I’m having omnivore company tomorrow and my go to is always a yummy vegan lasagna. But this time I’m really watching my calories and since I know dinner will include my husband’s homemade french bread and a key lime pie for dessert, I didn’t want the main dish to be so carb dense. Spaghetti squash! Perfect solution! I’m considering also making separate pesto and stirring it together with the squash to give the squash itself a little more flavor, since it can be bland.
Thanks for the excellent recipe, as usual!
LiviaJanuary 18, 2014 at 7:01 pm
I love your recipes and this one looks fabulous. Since I live alone, I cook in quantity and freeze most things.
Have you ever frozen this recipe? Results? Would you do it again?
Susan VoisinJanuary 20, 2014 at 12:26 pm
I haven’t frozen it, so I can’t say how it would do. But if you try freezing it, I’d love to know the results.
JeriJanuary 22, 2014 at 12:50 pm
I just made the spaghetti squash lasagna and it is DEEE-licious! I used my new pressure cooker for the squash and it worked well, although I had to add a couple of extra minutes cooking time. I used a whole jar of marinara sauce (I like lots!) and also added Field Roast Italian seitan sausage; the sausage is good, but next time I will leave it out to keep the fresh veggie flavors in the foreground. The tofu filling and cheese sauce are amazing! I will use them with traditional noodle lasagna, too. Thank you, Susan, for yet another fantastic recipe!
LiviaJanuary 25, 2014 at 9:55 pm
Can’t tell you how this lasagna freezes yet. I had 2 friends over for dinner last night and served the lasagna. I thought it was delicious and my guests thought so too. No leftovers and the plates were licked clean. I now have a new favorite entree.
Avriel O'ConnorMay 5, 2014 at 9:36 pm
I absolutely love spaghetti squash, I was looking for a vegetarian dish for this evening (my attempt to do a Meatless Monday) and to use up the squash I bought last week. I just made this recipe and it’s FANTASTIC. So much I had to come and let you know. I am going to make this again and have already notified a few of my vegan friends. Definitely a bit of work for a weeknight meal, but so worth it.
Carlee SavageMarch 16, 2019 at 4:43 pm
Has anyone made this lasagna in an Instant Pot???
HappeegalAugust 22, 2014 at 3:44 pm
Oh My Lord, Susan!!
I first saw this recipe on my facebook feed and thought it looked delicious and then I made it, and it was more than delicious, it was stupendous, amazing, out of this world :). I can’t eat mushrooms so I put in asparagus and it was great. I love this lasagna, you don’t even miss the noodles, and it’s just yummylicious.
I am so happy to have access to your website, I haven’t tried a recipe I haven’t liked yet. Keep up the great work and thank you.
LainaNovember 14, 2014 at 1:19 pm
This looks so delicious. Have you ever made it with dry basil? I’m not sure if I can find basil fresh right now. If I can’t, how much of the dry basil should I use?
Susan VoisinNovember 14, 2014 at 1:31 pm
I haven’t made it with dry basil and worry that it won’t be as tasty, but you could try adding it to taste.
Laura KiowskiDecember 4, 2014 at 12:47 am
This sounds wonderful. I’m inviting a friend over this weekend who is considering going plant based. I wondering if I made an extra dish would the squash freeze well or turn into a soggy pile of mush?
HeatherMarch 22, 2015 at 8:10 pm
This recipe is INSANE!!! I have loved every recipe of yours that I’ve ever tried. But this one knocked it out of the park. We ate almost the entire pan. Kids loved it, husband loved it, we all love it, and it’ll be made many more times.
Abigail TaylorMay 29, 2015 at 7:17 pm
Hi Sue, First of all. Thanks for being a blessing. I appreciate the way you share, telling us about your pets, allowing us to seem them, cats etc.,. I love your recipes and the way you explain and share as well. I am faced with a situation on this Island, in that we do not get certain food items here, such as potato starch, and Seitan, and other items, so I miss out in making the lovely, tasty looking dishes. One day Lord willing I will meet you and family in God’s time. Love and hugs. Abi.
Lynn WaltonOctober 19, 2015 at 12:00 am
Thanks so much for sharing this recipe online. I’ve been following Dr. Fuhrman’s Nutritarian style for a little over 9 months now and am still looking for dishes that meet the nutritarian criteria but can still be delicious. This is delicious, filling, creamy and seems like comfort-food! After making this tonight, it is one of my new favorites and I can see it being in our regular rotation for sure! Again, THANK YOU SO MUCH!
ConnieNovember 7, 2015 at 7:55 pm
I made this tonight and it was really delicious. My 17 year old son said that it was surprisingly good. I don’t think he knew what to expect when he noticed there were no lasagna noodles and spaghetti squash instead. I’ll definitely make this again. Thanks!
joyNovember 17, 2015 at 2:28 pm
My gosh! This was absolutely amazing! Tastes so good it makes you think its bad lol my sad eating 20 year old went back for seconds! I am definately making this again and doubling the recipe. The only thing i did different was i added red peppers and onion to the musshrooms step. Thanks for creating delicious healthy recipes!!
PamDecember 9, 2015 at 6:51 am
Can you freeze this/ before or after baking? Thank you
Susan VoisinDecember 9, 2015 at 7:01 am
I haven’t tried it, but I would worry that freezing would make the squash mushy and cause the casserole to be too liquidy.
KateJanuary 25, 2016 at 4:42 pm
making it now, my cheese sauce is just liquid, what’s the deal? Is it supposed to be thick?
Susan VoisinJanuary 25, 2016 at 5:14 pm
It thickens as it cooks.
john h =)July 14, 2016 at 2:09 pm
One teaspoon of salt? Isnt that alot of salt, and wont it over power the sweetness of the basil?
Susan VoisinJuly 14, 2016 at 5:18 pm
It’s just a suggested amount, but tofu is very bland and salt improves the flavor.
CarolynAugust 18, 2016 at 12:37 pm
I made this last night and it was amazing! I think I overcooked the spaghetti squash but I really liked it that way. I released the pressure right after it finished but I was busy with other things so I left the squash in the Instant Pot for about ten minutes. My strands were sort of mushy but they came out the squash effortlessly. I sort of pressed them into the pan with the spatula to make a nice base. I was amazed at how perfectly the lasagna sliced up and made it to the plate. It was very firm even though I was too impatient to wait more than about fifteen minutes to serve it. It is so good. It is less filling than lasagna made with noodles, of course, so I recommend generous portion sizes! I will definitely be making this again and again! Thank you!
EllenNovember 10, 2016 at 8:00 am
This recipe is amazing. I will make this again and again. I roasted the spaghetti squash in my slow cooker. This is a huge time saver. Just poke a few holes in it — you don’t need to cut the squash in half — and place it whole in the cooker. I roasted it on high for 3.5 hrs, and though I think it was cooked enough after 2.5-3 it was not overcooked. I cut it open and let it cool until I could handle it and then scooped the seeds; then after scraping it into the strands I let it sit for awhile in a collander. It was perfectly cooked for this recipe and I didn’t have too much liquid in the lasagna. The flavors in this dish are perfect. It also looks pretty. I can’t wait to make it again.
BethNovember 12, 2016 at 2:09 pm
I’m making this right now (it looks soooo good!), but the cheese sauce came out ay too thin, not at all like your picture. I’ll just add more cashews, but are the quantities right? I’m using cashew milk.
Susan VoisinNovember 12, 2016 at 2:33 pm
Have you already cooked it? It looks thin but should thicken during cooking.
BethNovember 12, 2016 at 2:52 pm
Not cooked yet, so I’ll give it a try and see how it turns out. Thanks for the quick reply!!!!!
HeatherJanuary 8, 2017 at 4:21 pm
Does anyone have suggestions for replacing the cashews in this recipe? My husband is a strict vegan for health reasons and my daughter has a very severe cashew allergy. As you can imagine that makes “cheesy” vegan dishes less accessible. The kids and I love, love, love cheese and we would still like to make this dish. Would almonds work? I understand it may not taste as cheesy, but would it be good, do you think? Other ideas are very welcomed!
Susan VoisinJanuary 8, 2017 at 8:04 pm
If your daughter can eat sesame seeds, try using 2 tablespoons of tahini instead of the cashews.
Teresa McDanielSeptember 25, 2017 at 12:01 pm
Just made this and it is AMAZING!! Why would anyone eat meat when real food can taste like this!! Thanks so much!!
LisaDecember 26, 2017 at 7:43 am
Really want to make this for new years, but my nephew is allergic to tree nuts and peanuts. What could I use instead of cashews? Thanks!
LisaDecember 26, 2017 at 7:45 am
Sorry I just saw the content about sesame seeds. Never mind! I’ll let you know how it turns out.
Susan VoisinDecember 26, 2017 at 8:23 am
I’ve also heard that sunflower seeds/butter are also good substitutes.
ChristinaJuly 22, 2018 at 1:04 pm
Wonderful flavors and texture! A bit too much salt in the filing, but otherwise the recipe was spot on! This is the first time I made something from this site and I’m so glad I did. I’ll be making the blueberry banana bread using GF flour next. I’m very happy I found this site since eating low fat, plant-based whole foods. Thank you Susan!
ShellySeptember 22, 2018 at 10:42 am
My first time trying one of your recipes… loved it! Low fat and vegan was what I was looking for…. this recipe fit the bill. I made it exactly per the recipe and will definitely be making it again. I can hardly wait to experiment with more of your recipe creations. Thanks for sharing!!!
Anne WeisbeckApril 24, 2020 at 1:42 pm
This was the first plant based recipe I made, and one of my favorites. Do you think the cheese sauce would work on top of pizza? I know it would be thin initially, but I was thinking of drizzling it on. Do you think it would thicken up like it does on the lasagna?
Susan VoisinApril 24, 2020 at 1:54 pm
That’s a great idea! I would cook it a little bit on the stove first—just until it starts thickening and remove it before it gets really thick. That way it wouldn’t just run off the pizza.
Anne M WeisbeckOctober 12, 2021 at 5:16 am
I know it’s been awhile, but I’ve used the sauce on pizza multiple times. I didn’t end up cooking it first and it worked fine
Anne WeisbeckOctober 12, 2021 at 5:14 am
Two and a half years ago when I was considering trying to go whole food plant-based, this was the first recipe I made. It was so good, so I jumped in to plant based eating with both feet. Since then, I have made it several time, most recently this past weekend. In that time period, I have made hundreds of recipes, and I have to say that this is my absolute favorite. It does take awhile to make, especially since I make homemade sauce for it, but if you have the time, it is so worth it. I usually double the recipe and we eat it all week. I have also used the cheese sauce portion on other foods, including homemade pizza.
Susan VoisinOctober 12, 2021 at 9:07 am
Thank you so much for letting me know. This is one of my favorites, too, and it’s great to see other people enjoying it.
JessicaOctober 18, 2021 at 12:10 pm
This was fantastic! Such a great comfort dish and we didn’t miss the pasta. The cheese sauce puts it over the top! In the fall/winter months your Pumpkin & Black Bean Casserole (I use butternut squash) is on constant rotation in my house. This one will also be added. Looking forward to trying other recipes. Thank you!
Ann H Smith-ReiserDecember 3, 2022 at 7:57 am
My entire extended family of omnivores LOVED this recipe. It was delicious! Will make this one often! Thanks!