Preheat oven to 350. Boil water and cook spaghetti as directed on box.

While it cooks, brown sausage. Drain fat and add sauce. Cover and simmer on low while pasta cooks.

Drain pasta, then stir sauce and pasta together. Transfer to oven safe dish. Top with Parmesan cheese, then mozzarella. Bake until cheese is melted and browned.