How to make
Crumble the biscuits and walnuts, add the cocoa. Melt the butter and add the powdered sugar and vanilla to them.
Stir the butter and biscuits well, break the egg in. Knead until you get a homogeneous mixture.
Divide it into 4 equal parts, form them into salamis and wrap in aluminum foil.
Leave them in the fridge for 4-5 hours. Cut them into slices and serve.