Debone all of your northern. Place butter (1/2 cup) in the bottom of a 9 x 13 inch pan. Melt and add cut pieces of northern in the pan. Salt and pepper to taste. Add garlic salt, paprika. Slice finely 2 onions and place evenly on top of fish. Cook at 300 to 350 degrees until done. Baste with liquid periodically. Great fish recipe.