Finely grind the walnuts and chop the ginger. Knead both with liqueur and marzipan. Mix flour and baking powder. Add quark, milk, oil, sugar, vanillin sugar and spices and knead to a smooth dough with the dough hooks of the hand mixer.
Place the dough on a lightly floured work surface and knead briefly with floured hands. Roll out the dough to a rectangle (approx. 25 x 40 cm). Spread the marzipan mixture on the dough with a knife.
Roll the dough into a thin roll and cut it into about 20 triangles (about 2 cm wide). Place on a baking tray lined with baking paper and bake in a preheated oven (electric range: 175 ° C/ gas: level 2) for approx. 18 minutes.
Meanwhile, mix icing sugar and lemon juice to a smooth glaze. While still warm, brush the corners with the mixture and sprinkle with ground pistachios. Results in about 20 pieces.