Whisk eggs with salt. Add sugar, vanilla sugar, oil and yoghurt. Mix flour with baking powder and fold in. Stir in the corn flour. Pour the dough into a greased baking sheet dusted with and with flour.
Bake in a hot oven at 180 ° C top / bottom heat for 20 minutes.
In the meantime, stir together the sour cream and eggs and after this time spread the mixture on the cake, bake for another 20 minutes.