If you want to make the Shepherd's Pie ahead of time, skip baking and cover until you are ready to heat it. To heat from cold, cover the pie with foil and bake at 350F (180C) for about 20 to 30 minutes until heated through. Remove the foil and crank the temperature to 425F (220C) and bake another 15 to 20 minutes until hot. Enjoy!