In a large saucepan with a tall lip, heat the olive oil over medium high heat and saute the onion and chopped garlic.
Add the sausage and break it down into small pieces as it browns.
Once the sausage is browned, add the diced tomatoes and tomato sauce.
Season the sauce salt, pepper, garlic powder and Italian seasoning.
Stir the sauce until everything is combined and let it cook for about 10 minutes over low heat.
Stir in the cream and continue to let it cook for another 5 minutes.
Add the pasta water and rigatoni to the sauce and stir everything together until the pasta is coated in the sauce.
Serve warm and with parsley, basil, parmesan cheese if you'd like to.