1 small butternut squash (about 1 pound), peeled, seeded, and cut into 1-inch cubes (about 3 cups)
1 cup Homemade Chicken Stock Homemade Chicken Stock
1 1/2 cups nonfat milk
Pinch of freshly grated nutmeg
Pinch of cayenne pepper
3/4 teaspoon coarse salt, plus more for water
Freshly ground black pepper
1 pound elbow macaroni
4 ounces extra-sharp cheddar cheese, finely grated (about 1 cup)
1/2 cup part-skim ricotta cheese
4 tablespoons finely grated Parmesan cheese (1 ounce)
2 tablespoons fine breadcrumbs
1 teaspoon olive oil
Olive-oil cooking spray