Peel the apples, remove the core and rub into a large bowl on the finest side of a grater. Remove the walnuts from the shell, remove the membranes and roughly chop. Add the cranberries, roughly chopped walnuts, sugar, cinnamon, gingerbread spices, ground cloves, cocoa powder and rum. Mix everything thoroughly, cover well and let this nut-fruit-spice mixture rest for 24 hours or let it steep.