In large bowl combine l/3 cup potato flakes with ground beef, egg, l/4 Cup milk, catsup, Worcestershire sauce, onion, 1/2 teaspoon salt and pepper. In shallow microwave-safe dish shape mixture into a loaf, about 8 inches long. Cover loosely with waxed paper; cook on Medium-High 9 to 12 minutes, turning dish once. Remove loaf to microwave-safe serving plate. Meanwhile in microwave-safe medium bowl combine water, remaining milk, butter, chives and remaining salt; stir in remaining potato flakes. Cook on High 3 to 4 minutes or until bubbling. Stir; let stand 1 minute; stir again Spread potatoes over loaf to cover. Top with cheese. Cook on High 1 to 2 minutes or until cheese is melted.