Cook the Pasta: Bring a large pot of salted water to a boil. Add the rigatoni pasta and cook according to the package instructions until al dente. Drain the pasta, reserving 1 cup of pasta water, and set aside.

Cook the Sausage: In a large skillet, heat the olive oil over medium heat. Add the sausage and cook, breaking it up with a spoon, until browned and cooked through, about 5-7 minutes. Remove the sausage from the skillet and set aside, leaving the drippings in the skillet.

Sauté the Onion and Garlic: In the same skillet with the sausage drippings, add the chopped onion and cook until softened, about 5 minutes. Add the minced garlic and cook for an additional 1 minute until fragrant.

Make the Sauce: Add the heavy cream, chicken broth, Parmesan cheese, dried oregano, dried basil, salt, black pepper, and red pepper flakes (if using) to the skillet. Stir well to combine and bring the mixture to a simmer. Let it cook for about 5 minutes, until the sauce has thickened slightly.

Combine the Pasta and Sauce: Add the cooked rigatoni pasta to the skillet with the sauce. Toss well to coat the pasta evenly. If the sauce is too thick, add some of the reserved pasta water to reach your desired consistency.

Serve: Transfer the Creamy Sausage Rigatoni to a serving dish. Garnish with chopped fresh parsley and additional grated Parmesan cheese. Serve hot and enjoy!