Step 1: Bring a large pot of water to a boil. Once boiling, add a generous amount of salt (about 1 tablespoon for every 4 quarts of water). Add the rigatoni and cook it until it is just shy of al dente, about 1 to 2 minutes less than the package instructions. Drain the pasta well and toss it with a drizzle of olive oil to prevent sticking. Set aside.

Step 2: In a large skillet or Dutch oven, heat a splash of olive oil over medium heat. Add the finely chopped onion and sauté until it becomes translucent and soft, about 5 minutes, stirring occasionally to prevent burning.

Step 3: Add the minced garlic to the skillet with the onion. Stir constantly and cook for about 30 seconds, just until fragrant. Be careful not to burn the garlic.

Step 4: Add the ground beef or sausage to the skillet. Cook, breaking it up with a wooden spoon, until fully browned and no longer pink, about 7 to 8 minutes. Carefully drain off any excess grease.

Step 5: Stir in the marinara sauce, scraping up any browned bits from the bottom of the skillet for maximum flavor. Season the sauce with dried oregano, basil, a pinch of salt, and a crack of black pepper. Reduce the heat to low and let the sauce simmer gently for 5 to 10 minutes, allowing the flavors to meld.

Step 6: While the sauce simmers, prepare the ricotta filling. In a medium bowl, combine the ricotta cheese, the egg, half of the grated Parmesan cheese, and a pinch of salt and pepper. Stir until smooth and creamy. Set aside.

Step 7: Preheat your oven to 375 degrees Fahrenheit. Lightly grease a 9×13-inch baking dish with olive oil or non-stick spray.

Step 8: In a very large mixing bowl, combine the cooked rigatoni with most of the meat sauce (reserve about 1/2 cup of sauce for topping). Gently toss everything together. Add dollops of the ricotta mixture throughout the pasta, folding it in gently without fully mixing—this way you will have delicious pockets of creamy cheese in every bite.

Step 9: Pour half of the pasta mixture into the prepared baking dish. Sprinkle half of the shredded mozzarella evenly over the top.

Step 10: Add the remaining pasta mixture on top. Pour the reserved meat sauce evenly across the top layer. Finish by sprinkling the remaining mozzarella cheese and the rest of the Parmesan cheese over everything.

Step 11: Cover the baking dish tightly with aluminum foil. Bake covered for 20 minutes to allow everything to heat through and the cheese to melt without drying out.

Step 12: Remove the foil and continue baking for an additional 10 to 15 minutes, or until the top is bubbling and golden brown. For extra crispiness, you can broil the casserole for 2 to 3 minutes at the end, but watch carefully to avoid burning.

Step 13: Once baked, remove the dish from the oven and let it rest for at least 5 to 10 minutes before serving. This helps the layers set, making it easier to slice and serve without falling apart.