This vegan version from The Joy of Cooking is delicious and pretty easy. You can also substitute a different kind of squash, depending on what you have on hand.
Butternut Squash Soup from The Joy of Cooking
1 large (or a few small) butternut squash, about 3.5 lbs
3 T. vegetable oil
2 large leeks, white part only, chopped
4 t. minced peeled fresh ginger
6 c. vegetable stock total, used in parts
1.5 t. salt
1. Cut squash in half, remove seeds, and place cut side up on a rimmed baking sheet. Add 1/4 inch water to the pan and cover with aluminum foil. Bake at 375 until tender, 30 to 45 minutes.
2. In a soup pot over medium low heat, heat 3 T. vegetable oil. Add the leeks and ginger and cook until leeks are tender but not browned, 5 to 10 minutes.
3. Scrape the squash from the skin and add it to the pot along with 4 c. vegetable stock. Bring to a simmer. Cook for 20 minutes, stirring and breaking up the squash.
4. Puree the soup in a blender or food processor until smooth. Return to the pot and add the rest of the stock and the salt. Heat through, then serve.
Makes 8 cups.