Steam melt the chocolate. Whip the eggs, sugar and vanilla sugar into a foam. Add room temperature butter and melted chocolate, then flour and baking powder.
Once all the ingredients have been connected and the dough is uniform, cover it and store in the refrigerator for two hours.
Preheat the oven to 180 degrees.
Put powdered sugar in a bowl (you will roll the balls in it). Spoon out the dough with a teaspoon, make it the size of a walnut. Shape the ball with your hands. Roll the shaped ball into powdered sugar. Transfer the rolled ball to the baking tray. Stack them making sure to leave a gap between each one.
Bake them for about 10 minutes at 180 °C.