Preheat the oven to 375°F (190°C).
Cook the ziti pasta according to package instructions until al dente. Drain and set aside.
In a large skillet over medium heat, brown the ground beef and Italian sausage, breaking it apart as it cooks. Add the chopped onion and minced garlic, cooking until the onion becomes translucent.
Stir in the crushed tomatoes, dried basil, dried oregano, salt, and pepper. Let the sauce simmer for about 10 minutes.
In a mixing bowl, combine the ricotta cheese, half of the mozzarella cheese, Parmesan cheese, egg, and a pinch of salt and pepper. Mix until well combined.
In a large bowl, combine the cooked ziti with the meat sauce, ensuring the pasta is well coated.
In a greased 9x13 inch baking dish, layer half of the ziti mixture, then spread the ricotta mixture over the top, and finally layer the remaining ziti mixture.
Top with the remaining mozzarella cheese. Cover the dish with aluminum foil and bake for 30 minutes.
Remove the foil and bake for an additional 15 minutes, or until the cheese is bubbly and golden.
Allow to cool for a few minutes before serving.