Babe Winkelman's wife had a recipe years ago on his show.
It was great.
Used to make this up at work for the guys, was great because we only had a Microwave in our lunch room.
Big glass pyrex dish cover the bottom with mayo, I used Miracle Whip, better taste, lay filets in it then cover with more Miracle Whip, then I sliced potatoes and onions as you would scalloped potatoes on top of everything, salt and pepper and a couple chucks of butter. I squeezed the potatoes and onions down in the mayo and fish, covered with saran rap and cook in the Micro.
Time is all about how much in the dish and micro size.
The mayo turned into a white sauce because of the fish jucies.
I kept checking while it was cooking , spooned sauce over like you would baste.
Was a bad thing to start at work, guys expected it every week