If using a medium butternut squash:

1. Wash butternut squash and cut in half. Take seeds out.
2. Brush squash with butter or olive oil.
3. Bake at 350° F until soft but not cooked (about 20 minutes).
4. Let cool for 10 minutes.
5. Scoop out pulp and set aside or refrigerate for use later.

For the soup:

1. Sautée onion and tomato with oil in large pot for 2-3 minutes.
2. Add squash to pot. Stir regularly for 2-3 minutes.
3. Add broth and simmer on medium-low heat until squash is tender (about 20 minutes).
4. Remove from heat and let cool (about 10-15 minutes).
5. Transfer while still warm to blender and purée. You  may want to divide soup into small batches and blend each batch separately to obtain a smoother texture. At this point, you can set aside a certain amount for freezing.
6. Return remaining soup to pot and bring back to boil. 
7. Mix in milk or cream, sour cream, salt and pepper. Remove from heat.
8. Garnish with chopped parsley if desired.

VARIATION: You can use one medium apple instead of tomato for a sweeter soup.

FREEZING: This soup freezes well. I usually freeze half of the soup after blending it. To reheat soup from frozen, transfer to pot, add some water and gently thaw, stirring regularly. Add sour cream, cream, salt and pepper and enjoy. You can also thaw it overnight in the fridge.