In a large skillet, melt the butter and sauté the onions over medium heat until soft. Add the squash, apple and garlic. Sauté for 3 to 5 minutes, stirring occasionally.
Add the flour, curry powder and nutmeg, stirring constantly to blend. Slowly add the broth, milk (or cream) and orange zest/juice, stirring constantly to combine. Simmer for 20 to 30 minutes until the vegetables are very soft.
Purée the soup in batches in a blender or food processor. Season with salt and pepper, to taste.
Serve hot and garnish with parsley, if desired.
Notes
*If you're preparing this recipe as GLUTEN FREE, just make sure that the brand of broth that you use is branded as gluten free, and use a couple of tablespoons of cornstarch to thicken instead of using flour.