First, prepare the brown layer. Beat the egg with the yoghurt and sugar, add the flour and baking powder. Bake in preheated oven until ready for 15 minutes. Remove, let it cool and cut out heart shapes.
Prepare the white layer. Beat the eggs with the sugar until whitened, add the yoghurt, then the flour with the baking powder. Mix up a smooth cake batter.
In an elongated baking form, greased with oil and sprinkled with flour, place 1/2 of the white mixture, arrange the brown hearts tightly on top and cover with the remaining white mixture. Bake 40 minutes until ready.
Slice the cake and you'll see the surprise!