-flakes) Preheat oven to 450. Cover broiler pan with aluminum foil and grease well. In med bowl mix mayonnaise, lemon juice, horserradish, Swiss cheese, Parmesan cheese, onion, hot pepper sauce and garlic salt. Add white pepper to taste. Fold in potato flakes and mix well. Spread mixture evenly over fish filets. Place filets on brolier pan. Reduce oven temperture to 400; bake for 10-15 mins. Turn oven to broil and cook until tops are golden brown. Fish flakes when done.