Grease a ring cake tin (approx. 2 l capacity) well and sprinkle with sugar. Drain the apricots and collect the juice. Cut the apricots into thin slices. Cut the biscuits in half.
For the batter, whisk butter, sugar, vanilla sugar and 1 pinch of salt until creamy. Stir in the eggs one by one. Mix flour and baking powder and stir in alternately with the milk.
Fold the apricots and biscuits into the dough and fill into the mould. Bake in the preheated oven (electric cooker: 175 °C/circulating air: 150 °C/gas: level 2) for 50-60 minutes.
Leave the cake to cool in the mould for about 10 minutes. Mix 5 tablespoons apricot juice and liqueur. Sprinkle warm cake with it. Let it cool down, then turn out of the tin.