This recipe is from my friend, Carolanne, who is from New Zealand. The idea was that for a Sunday Roast, in New Zealand, the family would have a roast leg of lamb. One of the meals prepared from leftovers was shepherds pie. As leftovers, you would include not just the meat, but also the mashed potatoes, the gravy, and vegetables, usually carrots and maybe peas, depending on the season. You can substitute ground beef for the lamb is you prefer. Enjoy!