Once the apples and squash in the soup pot are tender, puree the soup with an immersion blender
or carefully transfer it to a food processor fitted with a steel blade to puree in batches. Return soup to the pot once complete. Add 1 cup of the remaining chicken stock, then stir, adding a bit more stock as needed to reach your desired consistency (the soup will thicken somewhat when stored). Leave the texture fairly thick and rich. Stir in the salt, nutmeg, black pepper, and cayenne. Taste and add a bit more salt and pepper as desired. Serve hot, topped with sage croutons.