Meat (beef (cottage) or lamb (shepherds)), gravy and veggies (I like parsnips in this) topped with mashed potatoes. No pie crust.
Yummy.
Potatoes arrived in Europe from South America no earlier than the 16th century. My question was about how the "pie" was made prior to that ... and the answer was, with a grain-based crust and sweetened with fruit.
My mother, who is from Northern Ireland, made shepherd's pie with ground beef. In the U.S. from the 1940's on (at least) lamb was too expensive. We sometimes had leg-of-lamb at Easter, or when the Navy Commissary mysteriously had a batch of lamb-legs in stock.