In a bowl, mix flour, cocoa, vanilla and baking powder.
Pound the butter from icing sugar and add the egg. Mix everything well.
Gradually add the dry ingredients and then milk.
Put the finished dough on a pan with parchment in the form of cakes.
Bake 12 minutes at 180 degrees.
For cream, whip the cream with icing sugar and grease the cooled cookies, glue the Whoopi cake.