Cut top loin crosswise into 4 (4 ounce) cutlets. Place meat in a resealable plastic bag and pound with meat mallet or side of a heavy can. In a large, heavy skillet, heat 1/2 inch shortening to 365 degrees F (185 degrees C). While the shortening is heating, prepare cutlets. In a shallow bowl, beat together egg, buttermilk, salt and pepper. In another shallow dish, mix together garlic powder and 1 cup flour. Dip cutlets in flour, turning to evenly coat both sides. Dip in egg mixture, coating both sides, then in flour mixture once again.
Place cutlets in heated shortening. Cook until golden brown, turning once. Transfer to a plate lined with paper towels. Repeat with remaining cutlets. Drain grease, reserving 1/2 cup.
Using the reserved drippings in the pan, prepare gravy over medium heat. Blend in 1/4 cup flour to form a paste. Gradually add milk to desired consistency, stirring constantly. For a thicker gravy add less milk; for a thinner gravy stir in more. Heat through, and season with salt and pepper to taste. Serve over chicken fried steak.