Mix the butter, sugar, vanilla sugar and lemon zest until frothy. Then stir in the eggs one at a time. Mix the flour, baking powder and semolina and fold in together with the sour cream.
Place the dough on a baking sheet that has been greased or lined with baking paper and smooth it out. Cover evenly with the cleaned berries and bake in the oven at 180 degrees for about 30 minutes.
Dust them with a little icing sugar when they have cooled.