Beat butter, sugar and egg yolk until creamy . Knead in flour. Chill the dough for about half an hour and then roll out on a greased baking tray. Stir the jam until smooth and spread on the dough.
Beat the egg whites until very stiff, slowly adding the sugar. Fold the ground hazelnuts into the beaten egg white. Spread the mixture on the jam and bake in a preheated oven at 200C° for about 35 minutes.
After baking, let the cake cool down on the baking tray and then cut it into sticks about 1cm wide and 5cm long. It is best to leave the sticks open, so that the meringue stays crispy.