How to make
Stir together the butter, sugar, 3 yolks and 1 whole egg well.
Add the yoghurt, baking powder, baking soda and stir once again.
Sift the flour and add it to the resulting mixture.
Bake in a greased tray at 300°F (150 °C).
Beat the remaining 3 whites with 1 tbsp powdered sugar and pour it onto the cake layer, which you've smeared with honey or jam.
Sprinkle with walnuts and put it to bake a bit once again.
