Following the package directions; bring your pasta water to a boil.
Cooking the sausage: Heat a large skillet (12 in and 3 in deep) and add olive oil. When hot add the sausage cut side down, browning each cut side. When both cut ends have been browned add 1/4 cup of water cover and steam until cooked through.
Remove sausage from pan with a spoon leaving all the drippings in the pan. To the drippings add your onions and peppers, cook on a low heat. After 3-5 minutes add the garlic. DO NOT add it to early or you could burn the garlic and make it bitter.
When the onions are just transparent return the sausage to the pan and add the marinara sauce. Stir, cover and keep on low heat.
Place pasta in the boiling water. When it is done drain and stir into the sauce.
Add the Parmesan cheese to your liking and stir into the dish. Serve.