Beat the butter, clarified butter, sugar, lemon zest and salt until frothy. Gradually knead in the flour and sour cream. Shape the dough into a ball, wrap in foil and cool for approx. 2 hours.
Preheat oven to 180 degrees.
Roll out the dough thinly on a floured surface, cut out about 100 hearts. In half, cut out a heart with a smaller shape. Knead the rest of the dough and repeat the process. Bake the cookies on a baking tray lined with baking paper for 10-12 minutes. Let cool on a wire rack. Brush whole hearts with jelly and place the perforated hearts dusted with powdered sugar on top.