How to make
Finely crush the biscuits and mix them with the cocoa, vanilla and the crushed walnuts.
Separately rub the butter with the powdered sugar.
Add it to the biscuit mixture and mix it well again, until a homogeneous mixture is obtained.
Shape the salami by wrapping it in foil and leaving it in the fridge for at least 1 hour, so that it can harden.