Eggs are mixed with sugar and vanilla sugar. Then add the milk and oil. Mix the sifted flour with the baking powder and add it over the liquid composition.
In a bowl put 2 tablespoons of the composition, add cocoa and mix.
Wallpaper a cake tray with baking paper and a little oil. Pour the composition into the tray and put the cocoa composition on top.
Bake in the preheated oven for 30-35 minutes, watching from time to time so as not to burn.
When it has cooled, powder it with sugar.