Beat the butter until frothy. Add the sugar and egg yolk, then gradually add the almonds, the sifted flour and the cinnamon and knead everything into a smooth dough.
Chill in the refrigerator for half an hour.
Shape the dough into 60 small balls and place on a greased tray or baking paper. Make a recess with your index finger and add jam.
Bake at 175 ° C top / bottom heat for about 20 minutes.