01 - In a large skillet over medium-high heat, cook the ground beef or turkey with diced onion and minced garlic until browned and cooked through, about 7 minutes. Drain excess fat if necessary.
02 - Add mixed vegetables and beef broth to the skillet. Season with salt and pepper. Simmer the mixture for 10 minutes, stirring occasionally.
03 - Transfer the meat and vegetable mixture into a baking dish. Spoon the mashed potatoes evenly over the top and smooth with a spatula.
04 - Cover the assembled dish tightly with foil or plastic wrap and freeze until ready to use.
05 - Preheat oven to 375°F (190°C). Remove cover and bake the frozen shepherd’s pie for 45 to 55 minutes, until heated through and the topping is golden brown.