Grease the fat pan (32 x 39 cm; at least 3.5 cm deep). Drain the apricots. Mix flour, starch, baking powder, 200 g sugar, vanilla sugar, 1 pinch of salt, fat in flakes, eggs and 200 ml milk with the whisk of the hand mixer until everything is mixed well.
Cut the dough in half. Stir grated chocolate into one half of the dough. Stir 75 g sugar, cocoa and 5 tbsp milk into the other half of the dough.
Put both doughs alternately as blobs on the fat pan, pull through spirally with a fork and smooth them down.
Spread the apricots on the dough with the curvature upwards, press lightly. Bake in the preheated oven (electric oven: 200 °C/circulating air: 175 °C/gas: level 3) for about 35 minutes. Let them cool down. Dust with icing sugar before serving.