For the cake
Mix all the ingredients for 1 minute at the low speed and for 3 minutes at the medium speed. Serve the cake in a baking sheet 60×40cm and bake in a pre heated oven at 155°C for about 20-25 minutes.

When cold cut in thick slices and use a cutter to come to the result of the picture.

For the buttercream

Mix all the ingredients until you get a fluffy cream.