Fast and easy to put together, and everyone loves it. If haddock is not available, substitute any firm white-fleshed fish.
Preheat the oven to 350 degrees F. Cut the fillets into pieces that measure 2 inches by 3 inches. Place half the fish in the bottom of a 9-inch square baking dish. Combine the stuffing mix and melted margarine; set aside ½ cup. Spoon half of the remaining stuffing mix on top of the fish. Add another layer of fish and another layer of stuffing. Pour the soup over the casserole. Bake for 20 minutes. Spread the reserved ½ cup of stuffing over the top and bake for 10 minutes more. Serve hot.