Ingredients:

  Amount  Measure       Ingredient -- Preparation Method
--------  ------------  --------------------------------
   6                    halibut filets or any firm -- white fish cut 3/4"
     1/2  cup           mayonnaise
     1/4  cup           lemon juice
   1 1/2  teaspoons     horseradish
     1/2  cup           grated Swiss cheese
     1/3  cup           grated parmesan cheese
   2      tablespoons   minced onion
     1/8  teaspoon      hot pepper sauce
                        white pepper to taste
     1/2  teaspoon      garlic salt
     2/3  cup           Idahoan mashed potatoes -- (dry, flakes)

Preparation:

Preheat oven to 450. Cover broiler pan with aluminum foil and grease well. In med bowl mix mayonnaise, lemon juice, horseradish, 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 broiler pan. Reduce oven temperature to 400F and bake for 10-15 minutes. Turn oven to broil and cook until tops are golden brown. Fish flakes when done. Source: "Great Holiday Treats"