1Preheat oven to 350 degree F.
In a buttered 9x13 inch baking dish, lay fillets in a single layer. Do not stack fillets.
In a bowl, combine cheese, butter, mayonnaise, onions and seasonings. Mix well with fork.
Bake fish in oven for 10-15 minutes or until fish just starts to flake. Baking time will depend on the thickness of the fish you use.
Spread with cheese mixture and bake until golden brown, about 5 minutes. Watch fish closely so that it does not overcook.
NOTE: This fish can also be made in a broiler. Broil 2-3 minutes on each side. Then top with cheese mixture and broil another 2-3 minutes.
This is how I prefer making this fish - The Parmesan spread will pouf up as broiling...so darn good...