Snipped fresh chives and crème fraiche, heavy cream or sour cream for garnish
Preheat oven to 350º
Cut the squash in half lengthwise and scoop out the seeds.
Place the squash halves skin side down in a large roasting pan. Place a pat of butter (about ½ tablespoon) and 1 teaspoon brown sugar in the cavity of each.
Arrange the carrots and onion slices around the squash. Pour 2 cups of chicken stock in the pan. Cover tightly with aluminum foil and bake for 2 hours.
Allow vegetables to cool slightly, and then scoop out the squash flesh and put in a soup pot. Add the carrots, onions and cooking liquid.
Add the remaining 8 cups chicken stock, mace, ginger, cayenne and salt. Bring to a boil and then reduce heat and simmer for 10 minutes.
Purée the soup in batches and return it to the soup pot. (Use a blender, food processor, immersion blender or food mill.) Adjust seasonings and heat through. If you use a food mill, don't forget to scrape the bottom of the mill, lots of good stuff there.
Serve the purée garnished with snipped chives and a dollop of crème fraiche, sour cream or drizzle of heavy cream.
I like to garnish with pumpkin seeds also.
The immersion blender is the easiest, but the food mill is probably how I've made it most, I just really like the texture.