Cut the stale cake very thin. Peel and slice the Bananas. Put a layer of cake at the bottom of a buttered baking dish. Place over this a layer of the sliced Bananas. Pour over this a layer of milk custard, made from the above ingredients, and boiled very thin. Add another layer of cake, then one of Banana and custard, and so continue till you have used up all. Make the top layer of the custard. Put in an oven, cover with a piece of paper, bake for half an hour, and let the top brown slightly, and serve cold.