Bring a large pot of generously salted water to a boil.

Heat the olive oil in a large heavy pot or Dutch oven over medium heat. Add the sausage meat and cook for 7–8 minutes, crumbling it with a fork, until it is nicely browned and cooked through.

Add the chopped fennel and onion to the pot with the sausage. Sauté for 7 minutes, stirring occasionally, until the vegetables are tender.

Add the garlic, crushed fennel seeds, red pepper flakes, 2 tsp salt, and 1 tsp black pepper. Cook for 1 minute until fragrant.

Pour in the dry white wine and bring the mixture to a boil, scraping up any browned bits from the bottom of the pot.

Stir in the heavy cream, half-and-half, and tomato paste. Bring back to a boil, reduce the heat to low, and simmer, stirring occasionally, for 20 minutes, until the sauce has thickened significantly.

While the sauce simmers, add the rigatoni to the boiling salted water and cook according to the package directions until al dente (firm to the bite). Reserve 1 cup of the pasta cooking water, then drain the pasta.

Add the drained rigatoni to the sauce, stirring to coat the pasta completely. Cook over low heat for 5 minutes to allow the pasta to absorb some of the rich sauce.

Remove the pot from the heat. Stir in the parsley and 1/2 cup of the Parmesan cheese. If the sauce seems too thick, add a small splash of the reserved pasta water to loosen it. Serve hot in shallow bowls with the remaining 1/2 cup of Parmesan cheese passed at the table.