Bring a pot of salted water to a rolling boil, then cook the rigatoni or penne until al dente, about 10-12 minutes. Reserve 1/2 cup pasta water before draining and set aside.

Heat olive oil in a large skillet over medium-high heat until shimmering, then add the Italian sausage and break it apart with a spoon. Cook until browned, about 6-7 minutes, then remove and set aside while leaving drippings in the pan.

Add the diced yellow onion to the skillet and cook until softened, about 4-5 minutes. Keep the heat at medium-high so the pan stays active.

Add the minced garlic and tomato paste, stirring constantly, and cook until the paste darkens slightly, about 2 minutes. Scrape the bottom to prevent sticking.

Pour in the chicken broth and scrape up the browned bits from the bottom of the pan. Stir in the crushed tomatoes, red pepper flakes, dried Italian seasoning, salt, and black pepper, then simmer for 8-10 minutes.

Stir in the heavy cream and return the sausage to the skillet. Simmer for 2-3 minutes, until the sauce turns rosy and glossy.

Stir in the Parmesan cheese until melted, then add the cooked pasta and toss until fully coated. Use the reserved pasta water as needed to loosen the sauce and coat every piece.

Top with torn fresh basil and extra Parmesan before serving, so the herb stays bright. Serve warm from the skillet.