Pour the flour into a bowl and make a depression in the middle. Crumble the yeast into it. Heat buttermilk and 1 teaspoon sugar. Pour the yeast into the hollow and mix with some of the flour to make a pre-dough. Cover and leave to rise in a warm place for about 30 minutes
Add 2.125 g sugar, vanillin sugar, salt, butter in pieces and egg to the pre-dough. Knead to a smooth dough. Roll out on a greased baking tray (approx. 35 x 40 cm). Leave to rise in a warm place for another 20 minutes
Drain the apricots. Roughly chop trail mix. Spread the apricots on the dough with the curvature upwards. Sprinkle the trail mix over the apricots. Bake in the preheated oven (electric cooker: 175 °C / fan-assisted oven: 150 °C / gas mark 2) for about 30 minutes. Let the cake cool down. Then dust with icing sugar