How do you make butternut squash macaroni and cheese?

INGREDIENTS
1 small butternut squash (about 1 pound), peeled, seeded, and cut into 1-inch cubes (about 3 cups)
1 cup homemade or low-sodium canned chicken stock, skimmed of fat
1 1/2 cups nonfat milk
Pinch of freshly grated nutmeg
Pinch of cayenne pepper
3/4 teaspoon coarse salt
Freshly ground black pepper
1 pound elbow macaroni
4 ounces extra-sharp cheddar cheese, finely grated (about 1 cup)
4 tablespoons Parmesan cheese, finely grated (1 ounce)
1/2 cup part-skim ricotta cheese
2 tablespoons fine breadcrumbs
1 teaspoon olive oil
Olive-oil cooking spray or butter, to grease baking pan

DIRECTIONS

1.Preheat oven to 375°F. Combine squash, stock, and milk in a medium saucepan; bring to a boil over medium-high heat. Reduce heat to medium; simmer until squash is tender when pierced with a fork, about 20 minutes. Remove from heat.

2.Mash contents of saucepan; stir in nutmeg, cayenne, and salt, and season with black pepper. Stir to combine.

3.Meanwhile, bring a large pot of water to a boil. Add noodles; cook until al dente according to package instructions, about 8 minutes. Drain, and transfer to a large bowl; stir in squash mixture, cheddar, ricotta, and 2 tablespoons Parmesan.

4.Lightly coat a 9-inch square baking dish (4 inches deep) with cooking spray or coat with butter. Transfer noodle mixture to dish.

5.In a small bowl, combine breadcrumbs, remaining 2 tablespoons Parmesan, and oil; sprinkle evenly over noodle mixture.

6.Cover with foil, and bake 20 minutes. Remove foil, and continue baking until lightly browned and crisp on top, 20 to 40 minutes more. Serve immediately.