Biscuits are broken up into small pieces. Add ground walnuts and cocoa. Mix everything very nice. In separate bowl put the butter (not melted, but only slightly warmed) and powdered sugar and should be mixed very well with a fork or hand. Then mix the dry mixture and add vanilla and egg. Kneaded well. The finished mixture is divided into two parts - each is placed on a piece of transparent foil and formed of sausages, is screwed thereto. Put them in the refrigerator for 24 hours.