Preheat oven to 375°F (190°C).

1. Cook ziti in salted water until al dente. Drain and set aside.
2. Heat olive oil in a skillet over medium heat. Add onion and sauté until soft. Add garlic and cook for another minute.
3. Add ground beef or sausage (if using) and cook until browned. Drain fat.
4. Stir in marinara sauce, Italian seasoning, salt, and pepper. Simmer for 5–10 minutes.
5. In a bowl, mix ricotta cheese with egg (if using), 1/4 cup Parmesan, salt, and pepper.
6. In a large bowl, mix cooked pasta with half of the meat sauce and a handful of mozzarella.
7. Spread a layer of meat sauce in the bottom of a greased 9×13-inch baking dish.
8. Add half the pasta mixture, then dollop ricotta mixture evenly over it.
9. Add the rest of the pasta, top with remaining sauce, mozzarella, and Parmesan.
10. Cover with foil and bake for 25 minutes. Remove foil and bake for another 10–15 minutes, until cheese is golden and bubbly.
11. Let rest for 5–10 minutes. Garnish with fresh basil or parsley if desired.