Preheat your oven to 375°F (190°C).

In a large pot, bring salted water to a boil. Add in the rigatoni pasta and cook until al dente, usually about 8-10 minutes. Drain and set aside.

In a large skillet, heat the olive oil over medium heat. Add the chopped onion and garlic, cooking until softened (about 2-3 minutes). If using ground beef or sausage, add it now, breaking it apart as it cooks until browned. Season with salt, pepper, and Italian seasoning.

In the same skillet, add the marinara sauce to the meat mixture. Stir until well combined and warmed through.

In a large mixing bowl, combine the cooked rigatoni, sauce mixture, and ricotta cheese. Mix until everything is covered in sauce.

In a greased baking dish, spread half of the rigatoni mixture. Top with one cup of mozzarella cheese, then add the remaining rigatoni. Finally, sprinkle the remaining mozzarella and all of the Parmesan cheese on top.

Cover the dish with aluminum foil and bake for about 20 minutes. Remove the foil and bake for another 10 minutes or until the cheese is melted and bubbly, and slight browning is visible.

Remove from the oven and allow it to cool for about 5 minutes before serving. Enjoy your cheesy Baked Rigatoni with a side salad or garlic bread!