Bring a large pot of salted water to a boil and cook the ziti until al dente, about 8 minutes. Drain and set aside.

In a large skillet, heat olive oil over medium heat. Sauté chopped onions and minced garlic until fragrant and translucent.

Add ground beef or sausage, breaking it up and cooking until browned. Stir in marinara sauce and Italian seasoning, then simmer to blend flavors.

In a bowl, combine ricotta cheese, egg, half of the grated Parmesan, salt, and pepper. Mix until smooth to create the binding base.

Grease a baking dish. Layer half the cooked ziti, spread half the ricotta mixture evenly, sprinkle with half the mozzarella cheese, and add half the sauce.

Repeat these layers, finishing with a generous topping of the remaining mozzarella and Parmesan cheese.

Cover with foil and bake at 375°F (190°C) for 20 minutes. Remove foil and bake for another 10-15 minutes until cheese is bubbly and browned.

Let rest for 5 minutes before serving.