Beat the butter and sugar until foamy, gradually mix in the egg well. Mix in the remaining ingredients thoroughly and let the dough rest in the refrigerator for at least 2 hours.
Preheat the oven to 190 ° C. Line 2 trays with baking paper.
Shape the dough into balls by the tablespoon. Press down a little and place it on the sheets with a distance of at least 5cm. Bake the biscuits until golden brown for 18-20 minutes, leave to cool on the wire rack.