Boil ziti in salted water until al dente, about 8-10 minutes. Drain and set aside.
Prepare the Sauce:
In a pan, heat olive oil over medium heat. Sauté garlic and onion until fragrant. Add ground meat (if using), browning it. Stir in marinara sauce and Italian seasoning. Let it simmer for 5 minutes.
Layer the Ziti:
In a baking dish, spread a thin layer of sauce. Add a layer of pasta, then top with ricotta, mozzarella, and Parmesan cheeses. Repeat layers.
Bake:
Cover with foil and bake at 375°F (190°C) for 25 minutes. Uncover and bake for another 10 minutes to get a golden, bubbly top.
Serve:
Garnish with fresh basil or parsley. Serve with a side of garlic bread or salad.