Combine all ingredients except sweetener in blender. Blend at medium speed until smooth. Check sweetness and add sweetener to taste; blend once more.
Pour into a saucepan or microwaveable container and heat, stirring at regular intervals, until steaming. Pour into two mugs and serve.
You can easily take this from a beverage to a dessert by making it into pudding. Add 2 1/2 tablespoons of cornstarch to the mixture in the blender and blend well. Heat on the stove or in the microwave, stirring constantly (or once every minute in the microwave), until it boils and thickens. Pour into 4 dessert bowls and refrigerate until set.