Preheat the oven to 175 degrees. Combine butter and sugar with vanilla and beaten egg. Mix flour, baking powder and salt, add to the whipped mixture, knead the dough. Roll out the dough and cut out cookies from it, place it on a baking sheet covered with baking paper.
Bake cookies for 10 minutes in a preheated oven until the cookies turn golden. Dip in sugar and cool.