Heat the olive oil in a large skillet over medium heat. Remove the sausage from the casings, add it to the pan, and break it into small pieces. Cook until browned and fully cooked through.
Stir in the chopped onion and cook for about 3–4 minutes, until soft and translucent.
Add the minced garlic and cook for about 30 seconds, just until fragrant.
Pour in the canned tomatoes (with their juice), heavy cream, and chicken broth. Stir in the Italian seasoning. Let the sauce simmer for 3–5 minutes, stirring occasionally, until slightly thickened.
While the sauce is simmering, cook the rigatoni in salted boiling water according to package instructions until al dente. Reserve a little pasta water before draining.
Add the cooked rigatoni directly to the skillet with the sauce. Toss everything together until well coated. Add a splash of reserved pasta water if needed to loosen the sauce.
Stir in the grated Parmesan cheese. Season with salt and black pepper to taste.
Serve warm, topped with freshly chopped basil.