Cut the squash in pieces, discarding seeds, steam until very soft. Let cool, and scoop the meat away from the peel and set aside.
Fry onions and garlic in butter until soft and transparent (try toasting the garlic until golden brown before adding the onions, it adds to the nutty flavor of the soup).
Add broth and all the other vegetables and boil slowly until all the vegetables are very soft then blend in the blender or with a wand until smooth. Add a little more stock or water if you find it too thick.
Add spices, salt, pepper to taste at the end and let sit for a few minutes. Put a dollop of low fat yogurt in the bowl for something different.
Spice alternatives: Mexican - 1 tbsp pureed chipotle peppers, 1 tsp cumin, chopped cilantro to garnish. French - 1/2 cup white wine, 2 tsp palm rubbed marjoram. Indian - 1 1/2 tsp curry powder, 1 tsp pulverized coriander.
There are 78 calories in 1 serving of Butternut Squash, Carrot & Yam Soup.