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