Rotini Casserole - cooking recipe

Ingredients

1 lb. box rotini noodles, cooked
1 large onion
1 large jar spaghetti sauce with mushrooms
1 pkg. pepperoni, cut in half slices
1/2 stick butter
1 (8 oz.) shredded Mozzarella cheese

Preparation

Saute 1/2 stick of butter and onion in a pan.
Mix all of the ingredients together in a large bowl.
Place in a large casserole dish and bake at 350\u00b0 for 1/2 hour.