Shepherds Pie > See this recipe on-air on 09/22/2002 at 2:30 AM ET. > Recipe available for a limited time only. Why? Recipe courtesy Richard Gilbert 2 medium potatoes, cubed 1/2 cup milk 4 tablespoons butter, separated 1 pound ground beef 1 medium onion, 1/4-inch dice 1 medium carrot, 1/4-inch dice 1 medium celery stalk, sliced 1/2 pound mushroom, sliced 2/3 cup frozen peas 2 tablespoons fresh parsley, chopped 1 teaspoon dried thyme 1 teaspoon Worcestershire sauce 1/8 teaspoon nutmeg 1 cup brown gravy Salt and pepper Peel potatoes and cut into cubes. Place in cold salted water and bring to a boil, reduce heat to low boil until potatoes are fork tender, about 15 minutes. Drain potatoes and mash with milk and 2 tablespoons of the butter until smooth. Season with salt and pepper to taste and set aside. Brown ground beef in a large saucepan over medium-high heat. Remove ground beef from pan and drain off excess fat, reserving 3 tablespoons of fat. Put reserved fat in saucepan add onion, carrot, and celery. Sweat for 5 minutes until onion becomes translucent, add mushrooms, and frozen peas sauti for 5 more minutes. Return ground beef to pan along with parsley, thyme, Worcestershire, and nutmeg, simmer for 1 to 2 minutes. Add brown gravy to pan simmer 1 to 2 minutes, season to taste with salt and pepper. Remove from heat and let cool. Preheat oven to 400 degrees. Layer bottom of a 3-liter casserole dish with beef mixture, top with mashed potatoes making uneven peaks with a fork. Cut remaining butter into small cubes and sprinkle over mashed potatoes. Bake for 30 to 40 minutes until mashed potatoes have turned golden brown, remove from oven and let cool 5 minutes.