1 (7 oz.) pkg. thin spaghetti
1 stick butter
3/4 c. onion, chopped
1 lb. sausage
1 lg. jar Ragu chunky garden style spaghetti sauce
1 c. shredded Mozzarella cheese
1 c. shredded Cheddar cheese
1 c. shredded Swiss cheese
1 pkg. pepperoni, sliced
Black olives, halved