Finely grate or crush the biscuits, however you like. Add the sugar, cocoa (if using chocolate biscuits, do not use cocoa) and margarine as a binding ingredient.
Mix a homogeneous mixture by hand. Take small pieces of the resulting dough and shape balls with both hands until you run out of it.
Then roll them in ground walnuts. Put the cocoa balls in the refrigerator to cool. Bon appetit!