Roughly chop the apricots. Place in a bowl and sprinkle with liqueur. Coarsely chop the walnuts. Put 125 g butter in flakes, flour, baking powder, sugar, vanillin sugar, salt, stollen spice, eggs and quark in a mixing bowl and knead with the dough hooks of the hand mixer to a smooth dough.
Knead the apricots and nuts. Then place them on a well floured work surface, press them flat a little, spread Amarettini evenly on top and carefully knead in. Divide the dough into three equal parts.
Roll out each piece of dough into a rectangle (approx. 25x15 cm) on well floured work surfaces. Then form into a stollen. Place the stollen on a baking tray lined with baking paper and bake in a preheated oven (electric range: 175 °C/ convection oven: 150 °C/ gas: level 2) for 55-65 minutes.
If necessary, cover the stollen after about 35 minutes of baking time. Then remove from the oven and place on a grid. Melt 200 g butter, spread thinly on the still warm stollen and dust with a little icing sugar.
Repeat the process several times. Decorate as desired before serving with amarettini and walnut halves.