Preheat oven to 350°. Cook fettuccine as directed on package; rinse and drain well. Remove sausage from casings; cook in a skillet with the chopped onion until onion is tender and sausage is browned, breaking up the sausage as it cooks. Drain off excess grease. Toss together the fettuccine, sausage, onion, mushrooms, olives, 1 3/4 cups of the Cheddar cheese, and the pizza sauce. Turn mixture into a casserole; bake for 20 to 25 minutes, or until cheese melts and casserole is thoroughly heated. Sprinkle with the remaining Cheddar cheese and the Parmesan cheese the last 10 minutes of baking.
Pasta recipe serves 4 to 6.