The main ingredient of a traditional shepherd's pie is ground meat, typically lamb. This hearty dish consists of minced lamb cooked with vegetables such as peas, carrots, and onions, all simmered together in a savory sauce. The mixture is then topped with a layer of creamy mashed potatoes before being baked until golden and bubbling. While shepherd's pie traditionally features lamb, variations can also include ground beef, in which case it's often referred to as cottage pie. The dish is a comforting staple in British cuisine and is enjoyed for its rich flavors and satisfying texture.