Heat the oil in a large pot over medium heat. Add the diced onion and cook for 7 to 8 minutes until soft and translucent.

Stir in the minced garlic and add the Italian sausage. Cook for 7 to 8 minutes, breaking it into pieces, until well browned.

Add the canned tomatoes, blending them if whole. Stir in basil, oregano, red chili flakes, salt, and pepper. Bring to a boil, then reduce heat and simmer for 5 to 7 minutes.

While the sauce simmers, bring a large pot of water to a rolling boil. Salt the water generously and cook the rigatoni according to package directions until al dente, usually 9 to 11 minutes.

Reserve 1 cup of pasta cooking water, then drain the pasta.

Pour in the heavy cream and 1 cup of the Parmesan to the sauce. Stir on medium-low and simmer for 5 to 7 minutes until the sauce is glossy and slightly thickened.

Add the drained rigatoni to the sauce. Toss gently to coat, adding reserved pasta water as needed for desired consistency.

Plate immediately and sprinkle with the remaining 1/2 cup Parmesan and extra fresh basil. Serve hot.