In a large pot, bring salted water to a rolling boil over high heat. Add the rigatoni pasta and cook until al dente, about 8-10 minutes. Drain and set aside.

Return the same pot to medium heat and add the olive oil. Once hot, add the chopped onion and sauté for about 3-4 minutes until translucent.

Stir in the minced garlic and cook for 30 seconds until fragrant.

Add the spicy Italian sausage and break it up with a wooden spoon. Cook for about 5-7 minutes until browned.

Sprinkle in the red pepper flakes and stir for about one minute to toast them.

Pour in the crushed tomatoes and chicken broth, mixing thoroughly. Bring to a simmer.

Reduce heat to low and stir in the heavy cream. Season with salt and pepper to taste and let simmer for 3-5 minutes.

Add the cooked rigatoni back to the pot and toss gently into the sauce until coated.

Stir in the grated Parmesan cheese until melted into the sauce.

Serve hot, garnished with fresh basil leaves.