Set a large saucepan over medium-high heat and heat the butter for 1-2 minutes. Do not let it turn brown. Add the onion, celery and carrot and sauté for 5 minutes, taking care to turn the heat down if the vegetables begin to brown.
Add squash, apple, broth and water. Bring to boil. Cover, turn the heat down to a simmer and cook for 30 minutes or until squash and carrots soften. Puree, and return to a clean pot.
Add salt and spices to taste, and garnish with chives or parsley.