Deann's Potato Cheese Halibut

• 6 halibut filets
• 120 ml mayonnaise
• 100 gr idahoan mashed potatoes
• 60 gr swiss cheese (grated)
• 60 ml lemon juice
• 28 gr parmesan cheese (grated)
• 12 gr onion (minced)
• 7 gr horseradish
• 1 gr garlic salt
• 1 ml pepper sauce (hot)