Melting water bath chocolate and cow butter, stirring constantly. Then add the sugar and stir until its dissolution (we have removed the chocolate from the heat). Let the mixture aside to cool Knead dry ingredients: flour, cocoa, baking powder, salt and vanilla. In cooled chocolate mixture already tapping both eggs and confusion (I personally used the mixer, but can by hand with a wire whisk). Then repeatedly add flour mixture and stir well until a uniform slurry. Turn and put in the fridge to rest for 1 hour. When the mixture has thickened and cooled, hand take some of it and shaping the ball as walnut, which roll in powdered sugar. So shaped balls bake a tray covered with baking paper in a preheated 180 C oven for 15-20 minutes. The finished cookies should be slightly soft to the touch. Let them cool completely and then remove them from the pan. I personally recommend (unless you are able to eat them within a day or two) to store them in a closed box, will not dry out. Of this mixture were obtained about 50 sweet.