01 - Preheat oven to 375°F. Lightly grease a 9-inch springform pan with olive oil and line the bottom with parchment paper.
02 - Boil rigatoni in a large pot of salted water until very al dente, approximately 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. Add onion and sauté until translucent, 3 to 4 minutes. Add garlic, cook 1 minute longer. 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 - In a mixing bowl, combine ricotta, 1 cup mozzarella, Parmesan, egg, parsley, salt, and pepper. Mix until creamy and evenly blended.
05 - Arrange the rigatoni vertically, tightly packed, in the prepared pan. Using a piping bag or spoon, fill each pasta tube with the cheese mixture.
06 - Evenly pour tomato sauce over the filled pasta, allowing it to seep between noodles. Sprinkle the remaining 1 cup mozzarella over the top.
07 - Cover pan loosely with foil and bake for 30 minutes. Remove foil and continue baking for an additional 15 minutes, until cheese is golden and bubbling.
08 - Let dish rest for 10 minutes. Release the springform pan. Garnish with chopped parsley and additional grated Parmesan. Slice and serve warm.