1. Bring a large pot of salted water to a boil. Cook the rigatoni until al dente according to package directions. Reserve 1/2 cup pasta water and drain the rest. Set aside.

2. In a large skillet over medium heat, cook the sausage, breaking it up as it browns. Cook until no longer pink, then remove from skillet and set aside.

3. Add the diced onion to the skillet with some of the sausage drippings. Sauté until soft, about 3 minutes. Stir in garlic and cook for 30 seconds.

4. Stir in tomato paste and cook for 1 minute to deepen its flavor. Add heavy cream and stir until smooth. Season with salt and pepper.

5. Reduce heat and stir in mozzarella and Parmesan. Let the cheese melt, stirring until the sauce is thick and creamy.

6. Return sausage to the skillet along with cooked rigatoni. Toss gently to coat everything evenly. Add reserved pasta water as needed to loosen the sauce.

7. Let simmer for 2–3 minutes to blend flavors. Garnish with chopped parsley and serve hot.