1. Preheat the oven to 375 degrees Fahrenheit and grease a 9×13-inch baking dish.

2. Bring a large pot of salted water to a boil and cook the ziti until just shy of al dente. Drain and set aside.

3. Heat the olive oil in a large skillet over medium heat. Add the Italian sausage and cook, breaking it apart, until browned and fully cooked.

4. Add the diced onion and cook for 4 to 5 minutes until softened. Stir in the garlic and cook for 30 seconds.

5. Add the marinara sauce, tomato paste, Italian seasoning, red pepper flakes, salt, and black pepper. Simmer for 5 minutes.

6. Add the cooked ziti to the sauce and stir until well coated.

7. Spread half of the pasta mixture into the prepared baking dish. Dollop the ricotta over the top, then sprinkle with 1 1/2 cups mozzarella and 1/4 cup Parmesan.

8. Add the remaining pasta mixture and top with the remaining mozzarella and Parmesan.

9. Bake for 25 to 30 minutes until hot and bubbly and the cheese is melted and lightly golden.

10. Rest for 10 minutes, then top with chopped fresh basil and serve.