Preheat your oven to 375°F. Cook pasta according to package directions until al dente, drain, and set aside.
In a large skillet over medium-high heat, brown the ground beef and Italian sausage with the diced onion until the meat is cooked through and the onion is softened, about 8-10 minutes.
Add the minced garlic and cook for another minute until fragrant. Drain any excess fat.
Stir in the marinara sauce, tomato sauce, and Italian seasoning. Season with salt and pepper. Let it simmer for 5 minutes.
In a medium bowl, combine ricotta cheese, beaten egg, 1 cup mozzarella, ½ cup Parmesan, salt, and pepper.
In a greased 9x13-inch baking dish, mix together the cooked pasta and meat sauce until well combined.
Drop spoonfuls of the ricotta mixture evenly over the pasta, then gently swirl it in (it doesn't need to be perfectly mixed).
Top with the remaining 2 cups mozzarella and ½ cup Parmesan cheese.
Cover with foil and bake for 25 minutes. Remove foil and bake for an additional 15 minutes until the cheese is golden and bubbly.
Let it rest for 10 minutes before serving. Garnish with fresh basil if desired!