Fill a large pot with water, season it generously with salt, and bring it to a rolling boil. Add the rigatoni pasta to the boiling water and cook for 8-10 minutes until al dente.

In a large skillet, heat 2 tablespoons of olive oil over medium heat. Once the oil shimmers, add the diced onion and sauté for 4-5 minutes until it becomes translucent and fragrant.

Add 1 pound of Italian sausage to the skillet, breaking it up with a spatula. Cook for 6-8 minutes until the sausage is browned and fully cooked.

Stir in the canned tomatoes, including their juices, into the skillet with the sausage. Allow the mixture to simmer for 15 minutes over medium heat.

Lower the heat and slowly pour in 1 cup of heavy cream, stirring continuously to combine. Let the mixture simmer for an additional 5-7 minutes, allowing it to thicken slightly.

Add 1 cup of grated Parmesan cheese to the sauce, stirring until it melts in. If the sauce is too thick, gradually add some of the reserved pasta water until you reach your desired consistency.

Add the cooked rigatoni directly into the skillet. Use tongs or a large spoon to gently toss the pasta in the sauce, making sure each piece is evenly coated.

Transfer the creamy rigatoni to serving plates, garnishing generously with additional Parmesan cheese and fresh basil leaves.