1. Preheat your oven to 375°F (190°C). Cook rigatoni in salted boiling water until al dente. Drain and set aside.
2. Heat olive oil in a skillet over medium heat. Cook the ground beef until browned, seasoning with salt, pepper, and Italian seasoning. Stir in marinara sauce and simmer for 5 minutes.
3. In a bowl, mix ricotta, egg, and Parmesan cheese. Set aside.
4. In a large baking dish, layer half of the cooked rigatoni, half of the meat sauce, and dollops of the ricotta mixture. Repeat layers, then top with shredded mozzarella cheese.
5. Bake for 25-30 minutes, or until the cheese is melted and golden.
6. Let sit for 5 minutes before serving. Garnish with fresh parsley or basil if desired.