Mix flour with butter (you have to cut the butter in small pieces), then add powdered sugar, ground almonds and egg yolks. Work everything up into a crisp dough. Chill for half an hour (don't refrigerate it - cooling it suffices...).

Form thumb thick rolls from the dough and cut into 1 cm wide pieces (half an inch would be okay). Roll them until you get a 4-5 cm (about 2 inches) long string and form them into a crescent.

Bake them for 10-20 minutes at 180 degrees Celsius (356 degrees Fahrenheit), but be careful not to brown them too much.

Mix powdered sugar with vanilla sugar and turn the Kipferl around in the sugar mixture while still hot. Enjoy!