2 slices bacon
In a skillet cook bacon until crisp and drain, reserving 1 1/2 tablespoons fat. Crumble bacon.
In a heavy saucepan cook onion, leek, garlic, and bay leaf with salt and pepper to taste in reserved fat over moderate heat, stirring, until softened.
Add squash, 1/2 of the chopped appleapple, broth, and 1/2 cup water. Simmer mixture, covered, until squash is very tender, about 15 minutes, and discard bay leaf.
In a blender purée mixture in batches, transferring as puréed to a clean saucepan, and add enough additional water to thin soup to desired consistency.
Whisk in 2 Tbsp. sour cream and salt and pepper to taste and heat soup over moderately low heat until hot (do not boil).
Serve soup topped with crumbled bacon, Diced raw apple and a dollop of sour cream