Creamy Butternut Soup

2# Butternut squash (cut into chunks) (can use carrots or acorn squash)
4 cups chicken stock
1 ¼ cup sour cream
2 tablespoons butter
salt and pepper
¼ tablespoon cayenne pepper
1 tablespoon sugar

Combine squash and stock and bring to boil. Then simmer for 20 minutes or until very tender. Cool a bit and then puree the mixture. Return to medium low heat. Whisk in sour cream, butter, salt, pepper and cayenne. Add sugar according to taste. Serve with grilled shrimp or chopped herbs. Could garnish with pepper flakes and shelled pistachios.