Bring a large pot of heavily salted water to a rolling boil and cook the rigatoni according to package directions until al dente.

Before draining the pasta, carefully reserve about 1/2 cup of the starchy pasta water, then drain the noodles and set aside.

While the water boils, heat the olive oil in a large deep skillet or Dutch oven over medium-high heat.

Add the Italian sausage meat and cook, breaking it apart with a wooden spoon into bite-sized crumbles, until browned and cooked through, about 6-8 minutes.

Reduce the heat to medium, add the diced onion, and sauté until the onions are soft and translucent, approximately 4 minutes.

Stir in the minced garlic, crushed fennel seeds, and red pepper flakes, cooking for about 1 minute until the mixture is very fragrant.

Pour in the crushed tomatoes, stirring to scrape up any browned bits from the bottom of the pan, and bring the mixture to a gentle simmer.

Allow the sauce to simmer uncovered for 8-10 minutes until it has thickened slightly and the flavors have melded.

Reduce the heat to low and stir in the heavy cream and half of the Parmesan cheese until the sauce becomes a uniform, creamy orange color.

Add the cooked rigatoni to the skillet and toss vigorously to coat the pasta in the sauce, adding a splash of the reserved pasta water if needed to loosen the consistency.

Season with salt and freshly cracked black pepper to taste, then remove from the heat.

Serve immediately in warm bowls, topped with the remaining Parmesan cheese and torn fresh basil.