Fill a large pot with water, salt it generously, and bring it to a rolling boil. Cook rigatoni until al dente according to package directions. Reserve about 1/2 cup of the pasta water, then drain the pasta.

Heat a large skillet over medium heat. Add the Italian sausage, break it up, and cook until well-browned, about 6 to 8 minutes. Transfer the cooked sausage to a plate and keep warm.

In the same skillet, add the minced garlic and chopped onion. Sauté until the onion becomes soft and translucent, about 4 minutes.

Add the chopped tomatoes to the pan and cook until they soften and release juices, about 3 minutes.

Pour in the heavy cream, stir to combine, and bring to a gentle simmer. Let cook until the sauce thickens slightly, 2 to 3 minutes.

Return the browned sausage to the skillet. Stir to coat the meat in the cream sauce and heat through for 1 to 2 minutes.

Season with salt and freshly ground black pepper. If the sauce is thicker than desired, add reserved pasta water a tablespoon at a time until the texture is right.

Add the drained rigatoni to the skillet. Toss thoroughly so every piece is coated in sauce and the mixture is evenly combined.

Serve immediately, topping each portion with grated parmesan and torn basil.