Take a large deep fry pan and put in the olive oil and put on medium heat. Remove the casings from sausage and crumble the meat into the fry pan along with the chopped onions and cook slowly until sausage is lightly browned then drain.
Add the tomato sauce, wine, garlic,and diced tomatoes. Turn heat up to medium high and bring mixture to boil. Cover, reduce heat and simmer for 1/2 hour.
Turn heat back up to medium high and add the half and half. Bring mixture to slight boil. If you want thicker sauce mix corn starch with water and then add to sauce stirring in to desired thickness. Turn down heat and let simmer while you cook your rigatoni shells according to package directions.
Drain shells well. Serve individual serving of noodles with sauce spooned over. Top with parmesan cheese if desired.