Shepherd's pie (lamb) or cottage pie (ground/minced beef) is a meat pie with a crust or topping of mashed potato. The recipe has many variations, but the defining ingredients are minced red meat ("shepherd’s pie" refers to lamb filling and "cottage pie" refers to beef), cooked in a gravy or sauce with onions and sometimes other vegetables, such as peas, celery or carrots, and topped with a layer of mashed potato before it is baked. The pie is sometimes also topped with grated cheese to create a layer of melted cheese on top.