01 - Preheat oven to 375°F (190°C). Brush 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 just al dente, about 2 minutes less than package directions. Drain and toss with 1 tablespoon olive oil.
03 - Heat 2 tablespoons olive oil in a saucepan over medium heat. Cook onion until translucent, 3 to 4 minutes. Add garlic and cook 1 minute. Stir in crushed tomatoes, tomato paste, oregano, basil, and sugar. Season with salt and pepper. Simmer 15 to 20 minutes, stirring occasionally. Adjust seasoning as needed.
04 - In a mixing bowl, combine ricotta, 1 cup mozzarella, Parmesan cheese, egg, parsley, salt, and pepper. Mix until smooth.
05 - Arrange cooked rigatoni upright in the prepared pan. Using a piping bag or spoon, fill each piece of rigatoni with cheese mixture.
06 - Pour tomato sauce evenly over the pasta, allowing it to seep between tubes. Sprinkle remaining 1 cup mozzarella over the top.
07 - Cover loosely with foil and bake for 30 minutes. Remove foil and continue baking 15 minutes, until cheese is golden and bubbling.
08 - Let stand 10 minutes before releasing springform pan. Garnish with extra parsley and Parmesan. Slice and serve.