For the yeast dough mix 500 g flour, 50 g sugar, vanilla sugar, yeast and 1⁄2 TL salt. Melt 50 g butter, add milk and warm up. Add with eggs to the flour mixture. Mix everything with the dough hooks of the mixer at least
Knead for 8 minutes to a smooth elastic dough. Cover and leave to rise in a warm place for about 1 hour until the dough has doubled.
Grease a box mould (approx. 1 3⁄4 l capacity; 30 cm long). Briefly knead the dough on some flour and roll out to a square (approx. 50 x 50 cm). Spread with jam. Cut into approx. 36 squares and first cut into 6 strips (each approx. 8 cm wide).
Cut them crosswise into 6 squares (each approx. 8 x 8 cm). Stack 5-6 dough squares on top of each other and place them vertically in the mould (or see tip). Repeat the process until all squares are in the mould.
Cover and leave to rise in a warm place for about 30 minutes.
Preheat oven (electric cooker: 175 °C/circulating air: 150 °C/gas: see manufacturer). Spread 2 tablespoons of butter in flakes on the dough. Place the mould on a tray covered with aluminium foil.
Bake in a hot oven for 30-40 minutes. Cover with aluminium foil after about 20 minutes. Take out, let it rest in the form for about 30 minutes. Then carefully turn out and let it cool down.
Wash the currants, drain them and remove them from the panicles with a fork. Stir icing sugar with 1-2 tablespoons of water until smooth. Spread the icing and berries over the cake.