Preheat oven to 400 F. Cut the butternut in half lengthwise, and scrape out the seeds. Spray or rub a rectangular baking dish with oil (lightly) and place the squash in it cut-side down. Put the squash into the oven and set the timer for 15 minutes.
Meanwhile, put the cauliflower florets into a small, oiled baking dish of their own. After the squash has cooked for 15 minutes, put the cauliflower in with it. Bake, stirring every 10 minutes, until the cauliflower is beginning to brown and the squash can be pierced easily with a fork. (They will probably be finished at different times.) Remove from the oven and set the cauliflower aside.
Allow the squash to cool until it’s easy to handle, and scrape the flesh out of the skin and into a bowl. Use a fork or masher to mash it a little.
In a large saucepan, sauté the onion in a little water until it is translucent. Add the garlic and ginger and cook for about 3 more minutes, adding water as necessary. Add the squash to the pan along with the curry powder and the vegetable broth. Using a hand blender, blend the soup to a smooth puree. (Or, if you don’t have a hand blender, puree the soup in your blender in batches.) Reduce the heat to low, and cook for about 15 minutes.
Add the cauliflower to the soup. Taste for seasoning, and add sherry, salt, cayenne, and additional curry powder as needed. Cover and allow the soup to simmer until the cauliflower is tender. Add the orange juice, cook for 5 more minutes and serve.
Using good curry powder makes a huge amount of difference. If you like the curry powder you are using, that’s great, but if you often find that your curry dishes lack flavor or taste bitter or “off” in some way, it could be that your curry powder is old. Buying from spice stores, where the turnover is quick, or in small quantities from the bulk bins in natural food stores can help ensure that the curry powder you’re using isn’t months or even years old. My personal favorite mild curry powder is the Maharajah Curry from Penzey’s. It’s more expensive than most because it contains saffron, but every time I use it, I’m happy I ordered it. (No, they don’t pay me–darn it! I’m just a happy customer.)