Line an 8x8-inch tin with baking paper.
In a large bowl, break the digestive biscuits into medium-sized pieces then mix in the cranberries.
In a saucepan over low heat, melt the chocolate, butter and golden syrup together. Leave to cool 5 minutes.
Pour the melted chocolate mixture into the bowl with the biscuits and cranberries. Mix well.
Spoon the tiffin mixture into your lined tin and press it firmly into place.
Melt the chocolate for the topping and spread it evenly over the tiffin. Top with Christmas sprinkles.
Refrigerate your tiffin for 3 hours then cut it into squares, using a warm knife to prevent cracking.