01 - Preheat oven to 375°F. Grease a 9-inch springform pan with olive oil and line the base with parchment paper.
02 - Boil the rigatoni in a large pot of salted water until very al dente, about 2 minutes less than package instructions. Drain and toss with 1 tablespoon olive oil.
03 - Heat 2 tablespoons olive oil in a saucepan over medium heat. Add chopped onion and sauté until translucent, 3–4 minutes. Add minced garlic, cook for 1 minute. Stir in crushed tomatoes, tomato paste, oregano, basil, sugar, and season with salt and black pepper. Simmer for 15–20 minutes, stirring occasionally. Adjust seasoning as needed.
04 - In a mixing bowl, combine ricotta cheese, 1 cup mozzarella, Parmesan, egg, chopped parsley, salt, and black pepper. Mix until thoroughly combined and creamy.
05 - Arrange the rigatoni upright in the prepared pan, packed tightly. Using a piping bag or small spoon, fill each pasta tube with the ricotta mixture.
06 - Pour tomato sauce evenly over the filled pasta so it seeps between the noodles. Top with the remaining 1 cup mozzarella cheese.
07 - Cover loosely with foil and bake for 30 minutes. Remove foil and bake for another 15 minutes, until cheese is golden and bubbling.
08 - Let rest for 10 minutes before releasing the springform pan. Garnish with extra parsley and Parmesan. Slice and serve.