For the 5-minute cake, mix all ingredients except cocoa together for 5 minutes. Pour 2/3 of the batter into a buttered and floured cake pan.
Mix the rest of the batter with the cocoa and pour on top of the white batter. Fold through with a fork.
Bake the 5-minute cake at 180°C for about 1 hour.
If you wish, you can also cover the 5-minute cake with chocolate icing or dust it with powdered sugar.