Preheat the oven to 375°F (190°C).

In a large pot of salted boiling water, cook the ziti until al dente, according to package instructions. Drain and set aside.

In a large skillet, heat the olive oil over medium heat. Add the chopped onion and garlic, sautéing until soft and fragrant.

Add the ground beef or sausage to the skillet, breaking it apart with a spatula. Cook until browned, about 5-7 minutes. Drain any excess fat.

Stir in the marinara sauce, oregano, salt, and black pepper. Let it simmer for a few minutes.

In a large bowl, mix the cooked ziti with the meat sauce, ensuring every piece is well coated.

In a baking dish, spread half of the ziti mixture, then dollop half of the ricotta cheese on top. Add a layer of half of the mozzarella cheese, followed by the remaining ziti mixture, and finish with the rest of the ricotta and mozzarella cheeses. Sprinkle with Parmesan cheese.

Cover with aluminum foil and bake for 20 minutes.

Remove the foil and bake for another 10-15 minutes until the cheese is golden and bubbly.

Let it cool for a few minutes before serving. Garnish with fresh basil if desired.