Melt the chocolate and butter in a double boiler. Beat eggs, sugar and vanilla sugar until frothy. Mix the melted chocolate and butter lukewarm into the egg mixture. Gradually stir in the flour, baking powder and salt.
Cover the bowl with cling film and put in the refrigerator for 3-4 hours.
Then shape balls with a diameter of 2-3 cm, press them flat and then roll vigorously in the powdered sugar until the chocolate no longer shines through.
Place them side by side on a parchment-lined baking sheet. Leave 3 cm space between the biscuits.
Bake at 170 degrees top and bottom heat for 8-10 minutes.