Separate the egg whites and yolks. Mix the yolks with half the sugar, half the flour, 4 tablespoons of oil, 4 tablespoons of water and ½ a packet of baking powder.
Mix the egg whites with the other part of the sugar, half the flour and ½ baking powder. Then pour the mixture in layers in a pre-greased tray. Sprinkle cocoa between the layers.
Bake at 338°F (170 °C) for 40 minutes, with the fan on.