1. Peel the squash. Remove the seeds and string, then cut into 1- to 2-inch chunks. Toss into a large Dutch oven or soup pot. Add the leeks, milk, and water; salt generously and bring to a boil. Lower heat to a simmer and cook for 25 to 35 minutes, or until the squash is soft enough to mash when pressed lightly with the back of a spoon.
2. Using a blender or food processor, puree the soup in batches until it is very smooth. It may be thick: Thin to your desired consistency with milk or water. Season to taste with salt, pepper, and nutmeg. Reheat if necessary. (This soup is at its best when truly hot.)
3. To serve, ladle the soup into bowls, spoon over the apples and nuts, and garnish with a little crème fraîche or cream.
Serves 6. Per serving (without garnish): 180 calories, 32g carbs, 6g protein, 10mg cholesterol, 7g fiber, and 4.5g fat.
Next up: For dessert, enjoy these Baked Apples