How to make
Beat the butter with the sugar, add the egg yolks one at a time, then the flour, cocoa and rum.
Beat the whites into hard snow and gently mix them with the above products. You will get a cake batter, put it into a buttered baking dish and smooth it out.
Arrange walnut halves on top, next to one other. Bake at 340°F (170 °C) until ready.
