Cottage pie is a British meat pie made with a beef and gravy filling and a crust of mashed potatoes. It is very similar to shepherd's pie, which has a filling of lamb or mutton with a mashed potato crust. Originally a way to use up leftover roasted meat and cooked potatoes, cottage pie is now often made from raw ingredients. The dish probably dates to the 1700s when the use of potatoes first became widespread in Europe. There are many dishes from other countries that are very similar to both cottage and shepherd's pie.
Typically, cottage pie is made with beef while shepherd's pie uses lamb or mutton. The recipes are often so similar, that the names are used interchangeably at times. The term "cottage pie" appeared earlier in existing written records and dates to the late 1700s. Shepherd's pie was first recorded in the late 1800s, even though experts believe the dish is very likely at least 100 years older than that.
Older, traditional recipes using leftovers call for finely dicing the meat and using either leftover gravy to moisten it, or making a new gravy or sauce as a complement. Modern recipes usually use ground beef, called "minced" beef in Britain. Some recipes, including one 1894 recipe, include a layer of mashed potatoes on the bottom of the dish, but most recipes only specify an upper crust of potatoes.
Whether the potatoes are leftovers or cooked just for the cottage pie, they are usually mashed with milk and butter to make them lighter. Other vegetables such as chopped carrots, onions, and celery can either be mixed with the meat or layered on top of it before the topping of potato is spread. Many recipes recommend making the top of the potato crust rough, rather than spreading it smoothly, so the top of the pie browns better. Some also call for drizzling or spreading drippings, melted butter, or beaten egg on top of the potatoes to further aid in browning.
Another British meat pie, Cumberland pie, is also very similar to cottage pie. It has a meat filling with a mashed potato layer above that, but adds a layer of mixed bread crumbs and grated cheese on the very top. A North American version adds a layer of canned or creamed corn between the meat and potatoes. Hachis Parmentier, a French dish, uses chopped rather than ground beef, and calls for bouillon rather than gravy. Cheese is mixed into the potatoes in the French pie.