Bring a large pot of salted water to a boil and cook the rigatoni according to package instructions until al dente. Before draining, reserve 1 cup of the pasta water.

In a large skillet over medium heat, pour in the olive oil. Add the diced onion and cook for 3–4 minutes until softened.

Stir in the minced garlic and cook for an additional minute until fragrant.

Add the ground beef to the skillet, breaking it apart with a spatula. Cook until browned and fully cooked through, about 6–8 minutes. Drain any excess grease.

Stir in the tomato paste, Italian seasoning, red pepper flakes (if using), and a pinch of salt and pepper. Cook for 2–3 minutes to deepen the flavor.

Pour in the beef broth and heavy cream, stirring to combine. Allow it to simmer for 5–7 minutes, letting the sauce thicken slightly.

Gradually incorporate the Parmesan cheese, stirring until fully melted. Then, add the mozzarella and stir until smooth.

Toss the cooked rigatoni in the skillet, ensuring it’s coated with the creamy sauce. Add reserved pasta water as needed for your desired consistency.

Serve the creamy beef rigatoni on plates, garnished with fresh parsley or basil, and extra Parmesan on the side.