01 - Preheat oven to 375°F. Lightly grease a 9-inch springform pan with olive oil and line the base with parchment paper.
02 - Cook rigatoni in a large pot of salted boiling water until very al dente, about 2 minutes less than package instructions. Drain, toss with 1 tablespoon olive oil, and set aside.
03 - Heat 2 tablespoons olive oil in a saucepan over medium heat. Sauté onion until translucent, 3 to 4 minutes. Add garlic and cook for 1 minute. Stir in crushed tomatoes, tomato paste, oregano, basil, sugar, salt, and pepper. Simmer for 15 to 20 minutes, stirring occasionally. Adjust seasoning as needed.
04 - Combine ricotta, 1 cup mozzarella, Parmesan, egg, parsley, salt, and pepper in a bowl. Mix until fully blended and smooth.
05 - Arrange rigatoni upright in the prepared pan. Using a piping bag or small spoon, fill each pasta tube with the ricotta mixture.
06 - Evenly pour the tomato sauce over the filled pasta, allowing it to seep between the noodles. Top with the remaining 1 cup mozzarella.
07 - Cover pan loosely with foil and bake for 30 minutes. Remove foil and bake an additional 15 minutes until the cheese is golden and bubbling.
08 - Let rest for 10 minutes before releasing the springform pan. Garnish with extra parsley and grated Parmesan. Slice and serve.