Preheat oven to 375°F (190°C). Grease a 9x13-inch baking dish.
Cook ziti pasta according to package instructions. Drain and set aside.
In a large skillet, heat olive oil over medium heat. Add onion and garlic, sautéing until soft.
Add ground beef and cook until browned. Drain excess fat.
Stir in marinara sauce, diced tomatoes, Italian seasoning, salt, and black pepper. Simmer for 10 minutes.
In a bowl, mix ricotta, sour cream, and cream cheese until smooth.
Combine cooked pasta with the sauce mixture and mix well.
Layer half of the pasta mixture in the baking dish, spread the ricotta mixture over it, then top with the remaining pasta.
Sprinkle mozzarella and Parmesan cheese over the top.
Bake uncovered for 25 minutes, or until cheese is bubbly and golden.
Remove from oven, garnish with fresh parsley, and serve warm.