One Skillet Shepherd's Pie. Need recipes and ideas for easy weeknight dinners and meals? This is one of those classic comfort foods for fall or cold weather in the winter. Cook this simple and easy dish in your favorite cast iron pan. You'll need mashed potatoes: russets, butter, milk. Filling: Frozen grocery medley with peas, carrots, green beans and corn, ground beef, ketchup, onion and garlic powder.