Bring a large pot of salted water to a rolling boil. Cook the rigatoni until al dente. Drain and reserve about 1/2 cup of the pasta water. Set the pasta aside.

Heat a large skillet over medium. Add crumbled Italian sausage and brown it, stirring occasionally, until well caramelized, about 6 to 8 minutes. Transfer the sausage to a plate and keep warm.

In the same skillet, add the minced garlic and chopped onion. Sauté until the onion becomes soft and translucent, about 4 minutes. Scrape up any browned bits for extra flavor.

Stir in the chopped tomatoes and cook until they soften and begin to release their juices, about 3 minutes.

Pour in the heavy cream and bring to a gentle simmer. Stir until the sauce thickens slightly, about 2 to 3 minutes. If the sauce gets too thick, add a splash of the reserved pasta water.

Return the browned sausage to the skillet. Season with salt and plenty of freshly ground black pepper, and heat through for a minute or two.

Add the drained rigatoni to the skillet. Toss gently until every piece of pasta is coated with sauce and sausage is evenly distributed. Use reserved pasta water to adjust consistency as needed.

Serve immediately, topped with grated Parmesan and torn basil leaves.