Place butter in 4-quart saucepan and sauté onions over medium heat until onions turn opaque. Add squash, ginger, garlic and sauté an additional 2 minutes. Add bourbon and ignite with a lighter until alcohol has burned off.
Add chicken stock and simmer for 20 minutes. Add all other ingredients and simmer for 5 or more minutes.
Blend all ingredients in saucepan with a handheld immersion mixer or blender until all of the soup has been pureed very fine, then add salt and pepper to taste.