Combine flour and sugar in a blender bowl, add liqueur.
In another bowl beat egg whites to stiff peaks.
Gently fold the sugar-almond mixture into the egg whites, spoon by spoon.
Sprinkle the table with powdered sugar. From the resulting dough, roll a sausage with a diameter of 3-4 cm, cut it into pieces. Roll each piece into a ball, dusting it in powdered sugar.
Place the cookies on a baking sheet lined with baking paper; they will increase in size only slightly.
Bake for about 20 minutes on top level of your oven.