First separate the eggs. Cream egg yolks, butter, powdered sugar, vanilla sugar and the grated zest of 1/2 lemon.
Mix whole wheat flour with baking powder and stir in.
Spread into a greased and floured cake pan and spread the blackberries on top. Bake at 200 °C until almost done.
In the meantime, beat the egg whites until stiff, then gradually add the granulated sugar and continue to mix until you have a very firm mixture. Spread over the blackberry cake.
Bake at approx. 180 °C for another 5-8 minutes. The cake is ready when the snow cover is lightly browned.
Preparation Tip:
If you like, you can also make the blackberry cake with a little cinnamon. This harmonizes particularly well in terms of taste