In a large pot, bring salted water to a boil. Add rigatoni and cook until al dente, about 8–10 minutes. Drain and reserve a cup of pasta water.

In a skillet, heat olive oil over medium heat. Add Italian sausage and cook until browned and cooked through, about 5–7 minutes.

Add chopped onion to the skillet with sausage, sauté for 3–4 minutes until soft and translucent.

Stir in minced garlic and red pepper flakes, cooking for an additional minute.

Pour in crushed tomatoes, mix well, and bring to a gentle simmer for 10 minutes.

Lower heat and stir in heavy cream, simmer for another 5 minutes.

Add drained rigatoni to the skillet, tossing to coat. Add reserved pasta water if sauce is too thick.

Mix in grated Parmesan cheese until melted and taste, seasoning with salt and pepper.

Garnish with fresh basil and serve immediately.