Prepare white sauce as package directs. Cut unpeeled red potatoes in 1 cm thick rounds. (If using other potatoes, peel first.) Oil 13 x 9 x 5 cm baking dish; arrange potato slices on bottom, put still frozen fish in center. Spoon all but quarter cup white sauce over. Cover dish with foil; bake at 200ºC or 40 minutes. Discard foil. Arrange broccoli spears around fish, spoon reserved white sauce over. Sprinkle bread crumbs over all. Bake for 10 minutes or until fish is opaque in center. Makes 4 servings.