Cook the rigatoni in a large pot of salted boiling water according to package directions until al dente. Reserve 1/2 cup of the pasta cooking water, then drain the pasta and set it aside.

Heat the olive oil in a large, deep skillet or Dutch oven over medium-high heat. Add the sweet Italian sausage, breaking it up with a wooden spoon, and cook until it is beautifully browned and no longer pink, about 6 to 8 minutes.

Reduce the heat to medium, then stir in the chopped yellow onion, minced garlic, and crushed fennel seeds. Cook for 3 to 4 minutes, stirring occasionally, until the onion is soft, translucent, and highly fragrant.

Pour in the crushed tomatoes and season with a pinch of salt and black pepper. Bring the sauce to a gentle simmer, turn the heat to low, and let it bubble gently for 10 minutes to allow the flavors to meld.

Stir the heavy cream into the tomato sauce and let it warm through for about 2 minutes until the sauce turns a velvety, pale orange color.

Add the cooked rigatoni and the reserved pasta water to the skillet. Toss and stir over low heat for 1 to 2 minutes until the pasta is thoroughly coated in the glossy sauce.

Remove the skillet from the heat, then fold in the grated Parmesan cheese and torn fresh basil. Serve immediately in warm bowls with an extra sprinkle of Parmesan and a crack of fresh black pepper.