01 -
Preheat the oven to 220°C (425°F). Generously grease the bottom and sides of a 23-by-33 cm (9-by-13 inch) casserole dish with butter.
02 -
In a medium bowl, stir together the marinara sauce, beef broth, tomato paste, garlic, 1/2 teaspoon salt, and 1/4 teaspoon pepper.
03 -
Spread half the rigatoni in an even layer at the bottom of the prepared dish. Scatter half of the sausage by breaking it into pieces and dolloping onto the pasta. Dollop half of the ricotta over the layer. Pour half of the marinara mixture on top.
04 -
Repeat the layering with the remaining rigatoni, sausage, ricotta, and marinara mixture.
05 -
Cover the dish with aluminum foil and bake for about 50 minutes, or until the pasta is al dente.
06 -
Uncover the dish and sprinkle the shredded mozzarella evenly on top. Bake for an additional 10 minutes, or until the mozzarella is melted and bubbly.