Strain the icing sugar through a fine sieve. Put all the ingredients in a bowl and knead into a dough, first with the dough hook, then with your hands. Form 10 thumb-thick rolls from the dough and chill, covered, for 30 minutes. Cut the rolls into finger-thick slices and press grooves into them with a fork. Preheat the oven. Bake the pastry with sufficient spacing on a baking tray lined with baking paper at 175 °C top/bottom heat for approx. 16 min. Dust with icing sugar while still warm.