Mix butter flour and egg yolk in a planetary mixer equipped with a paddle until you obtain an even dough. Let it rest for at least 20 minutes in the refrigerator. Roll out the dough to about 1 cm thickness and then cut out in circles (diameter 2,5 cm) with a cake cutter. Roll the dough with the hands into small balls and place on greaseproof paper and bake at about 170-180°C for 10-15 minutes. Let cool and stick the "Kisses" together with PASTA BITTER or dark chocolate.