Preheat oven to 375°F. 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 diced onion and cook until translucent.
Add ground beef or sausage and cook until browned; drain excess fat.
Stir in minced garlic, crushed tomatoes, tomato sauce, basil, oregano, salt, and pepper. Simmer for 10 minutes.
In a mixing bowl, combine ricotta cheese, beaten egg, and fresh parsley.
Mix cooked ziti with half of the sauce.
Layer half of the pasta mixture in the baking dish, top with half of the ricotta mixture and half of the shredded mozzarella.
Repeat layers and top with grated Parmesan cheese.
Bake uncovered for 25 minutes, or until cheese is melted and bubbly.
Let rest for 5 minutes before serving. Enjoy!