Soak the raisins and cranberries in the rum for at least 2 hours, preferably overnight.
In a large bowl - crush the sponge and biscuits. It's good to leave some biscuits to have larger pieces.
Melt chocolate with butter.
Add the rest of the ingredients to the bowls, cranberry and raisins add together with rum. Miix everything well.
Form identical balls from the prepared mass using a small ice scoop, and then coat them in coconut flakes.