1.  In a mixing bowl, combine the cake crumbs, walnuts, golden syrup and rum.

2.  Melt the butter and jam together in a small saucepan over low heat until just melted. Stir into the cake mix until just combined.

3.  Add the grated chocolate, and mix well. Check the consistency - you want to be able to roll a chocolate truffle-sized ball (about 1 inch) that is firm enough to hold its shape, and is not too wet or greasy. If the mix feels too wet, add extra cake crumbs, or small handfuls of hazelnut meal, until it is the right consistency.

4.  Roll mix into balls, coat in chocolate sprinkles, and store in the fridge until needed - they keep very well refrigerated for at least a couple of weeks.

If desired, you can decorate your rum balls with some melted white chocolate and red and green lollies to make them look like tiny Christmas puddings!