Step 1: Preheat Oven : Preheat your oven to 375°F (190°C). Grease a 9x13-inch baking dish lightly with olive oil or cooking spray.

Step 2: Cook the Pasta : Bring a large pot of salted water to a boil. Cook ziti according to package instructions until al dente. Drain and set aside.

Step 3: Prepare the Sausage Sauce : In a large skillet, heat olive oil over medium heat. Add diced onion and cook for 3–4 minutes until translucent. Add garlic and cook for 30 seconds until fragrant. Add Italian sausage, breaking it up with a spoon, and cook until browned and fully cooked. Stir in crushed tomatoes, basil, oregano, salt, and pepper. Simmer for 8–10 minutes, stirring occasionally.

Step 4: Combine Pasta and Sauce : In a large mixing bowl, combine cooked ziti, sausage tomato sauce, and ricotta cheese. Mix until pasta is evenly coated with sauce and ricotta.

Step 5: Assemble the Casserole : Transfer half of the pasta mixture into the prepared baking dish. Sprinkle half of the shredded mozzarella and Parmesan cheese over the pasta. Add the remaining pasta mixture on top, followed by the remaining mozzarella and Parmesan.

Step 6: Bake : Cover the dish with aluminum foil and bake for 20 minutes. Remove the foil and bake for an additional 10–15 minutes until cheese is melted, bubbly, and lightly golden on top.

Step 7: Serve : Let the baked ziti rest for 5 minutes before serving. Garnish with chopped fresh parsley or basil if desired. Serve warm as a main course.