Mix all ingredients, add the cold butter in flakes at the end and knead quickly to form a smooth dough. Form three rolls with a diameter of 2 cm and put in a cool place.
In the meantime, preheat the oven to 200 degrees top / bottom heat or 175 degrees circulating air.
Cut 1/2 cm thick slices from the dough rolls and place on a baking sheet lined with baking paper. Bake for about 12 minutes and then dust with powdered sugar.