Cook the Pasta
Bring a large pot of salted water to a boil. Add the rigatoni and cook until al dente, according to package instructions. Reserve 1 cup of pasta water, then drain and set aside.
Brown the Sausage
Heat olive oil in a large skillet over medium heat. Add the sausage and cook, breaking it into small pieces, until browned and cooked through. Remove from the skillet and set aside.
Sauté the Aromatics
In the same skillet, add the chopped onion and garlic. Cook until softened and fragrant, about 3–4 minutes.
Prepare the Sauce
Stir in the crushed tomatoes and bring to a simmer. Reduce heat to low and stir in the heavy cream. Let the sauce cook for 5 minutes, allowing the flavors to meld.
Combine with Sausage
Add the cooked sausage back to the skillet and mix well. Season with salt, pepper, and red pepper flakes if desired.
Toss the Pasta
Add the cooked rigatoni to the sauce, tossing to coat evenly. If needed, add reserved pasta water a little at a time to reach your desired consistency.
Finish with Cheese and Basil
Stir in the grated Parmesan and mix until melted and creamy. Garnish with fresh basil and serve immediately.