Preheat oven to 350. Rub squash halves with oil, season with salt and pepper, and roast until soft, about 30-45 minutes. Let cool and scoop out flesh, discard skin
Put a large pot on a high heat and add 1/4 cup oil. Add onions, celery, carrots, garlic and chile and saute until soft. Add squash, rosemary, chicken stock and bring to a boil. Add nutmeg, cinamon and pepper, reduce to simmer for 30 minutes. Use immersion blender to puree soup until smooth. Adjust seasoning with salt.
Heat olive oil in a nonstick pan and add sage leaves. Fry leaves until crisp. Use oil from pan to moisten one side of bread slices and press grated cheese onto it. Drain most of remaining oil from pan and fry bread until crisp on both sides.
Pour soup into bowls, add fried sage leaves, drizzle with good quality extra virgin olive oil, and serve with the crostini.