Preheat your oven to 375°F (190°C).
Cook the ziti pasta according to package instructions until al dente. Drain and set aside.
In a large pot over medium heat, heat the olive oil. Add the diced onion and minced garlic, cooking until softened (about 3-4 minutes).
Add the ground beef and Italian sausage to the pot. Cook until browned, breaking the meat into small pieces (around 6-8 minutes).
Stir in the crushed tomatoes, Italian seasoning, salt, and black pepper. Let the sauce simmer for 10 minutes.
In a large mixing bowl, combine the cooked ziti pasta with the ricotta cheese, half of the mozzarella cheese, and ½ cup of the grated Parmesan cheese. Mix well to coat the pasta.
In a greased 9x13 inch baking dish, add a layer of the meat sauce followed by half of the ziti mixture. Repeat the layers, finishing with the remaining meat sauce on top.
Sprinkle the remaining mozzarella and grated Parmesan cheese over the top.
Cover with aluminum foil and bake in the preheated oven for 25 minutes. Remove the foil and bake for an additional 15 minutes, or until the cheese is bubbly and golden brown.
Remove from the oven and let it cool for a few minutes. Garnish with fresh basil leaves if desired, and serve warm.