Preheat oven to 375°F (190°C).

Cook ziti pasta according to package directions until al dente. Drain and set aside.

In a large skillet, heat olive oil over medium heat. Add onion and cook until soft, about 3–4 minutes.

Add garlic and cook for another 1 minute. If using ground meat, add it now and cook until browned. Drain any excess fat.

Stir in marinara sauce and let it simmer for 5 minutes. Season with salt, pepper, and Italian seasoning.

In a large bowl, mix ricotta cheese, sour cream, egg, 1 cup of mozzarella, and Parmesan cheese.

In a greased 9×13-inch baking dish, layer half the pasta, half the meat sauce, and half the cheese mixture. Repeat the layers.

Top with remaining 1 cup mozzarella cheese.

Cover with foil and bake for 20 minutes. Remove foil and bake for an additional 10–15 minutes, or until bubbly and golden.

Let sit for 5–10 minutes before serving. Garnish with fresh basil or parsley if desired.