Cook pasta in a large pot of salted, boiling water until al dente. Reserve 1 cup of pasta water. Drain pasta.
1 pound rigatoni pasta
Heat oil in a large pan over medium-high heat. Add the chopped onion and saute for 5 minutes until it starts to soften. Add garlic and sausage. Cook for another 6-8 minutes until the sausage is browned, breaking up the sausage into crumbles while it cooks.
2 Tablespoons olive oil, 1/2 large yellow onion,, 4 cloves garlic,, 1 1/2 pounds spicy or sweet Italian sausage,
Add crushed tomatoes, basil, oregano, red pepper flakes, salt, and pepper. Bring to a boil then reduce heat to medium-low and simmer for 10-20 minutes to reduce and thicken the sauce.
1 (28-ounce) can crushed tomatoes, 1/4 cup fresh basil,, 2 teaspoons dried oregano, 1/2 teaspoon red pepper flakes, 1 1/2 teaspoons kosher salt, 1/2 teaspoon freshly ground black pepper
Stir in heavy cream and 1 cup of the cheese. Simmer until heated through and the cheese has melted.
1 cup heavy cream, 1 1/2 cups freshly grated Parmesan or Pecorino-Romano,
Add cooked pasta to the sauce and stir to combine. Add as much of the reserved pasta water as you like to get a nice glossy texture. I typically use about 1/2 cup.
1 pound rigatoni pasta
Serve with remaining Parmesan cheese and fresh basil sprinkled on top.