Preheat the oven to 180C for 15 min. Sieve flour and baking powder, keep aside. Beat together the eggs, caster sugar and butter until smooth in a large mixing bowl.
Put the cocoa in a small mixing bowl, and add the water and make a stiff paste. Add to the cake mixture.
Now add flour and mix gently, make a smooth paste. Pour in a grace tin. Bake in the preheated oven for about 25 to 30 mins, or until shrinking away from the sides of the tin and springy to the touch.
After 10 min turn on to a wire rack to become completely cold before icing. After that cut into three layers and put whipped cream into each layer.
After that you can make any design and use some food gel