Knead the butter, sugar, egg yolk, salt and flour quickly into a dough. Divide the dough into 4 parts and shape into rolls (4 cm diameter). Wrap in kitchen foil and put in the fridge for 1 hour.
Cut approx. 4 mm thin slices from the rolls and place on a baking sheet lined with baking paper. Beat the egg whites lightly and brush the biscuits with it. Mix the sugar and cinnamon and sprinkle on top. Bake the cookies in the preheated oven for 8-10 minutes (electric stove 200 ° C). Take out and let cool.
Warm up currant jelly and put two cookies together with a little jelly.