Sprinkle cake layers with 5 tbsp (75ml) of the rum.
Melt chocolate in bowl over pan of hot water and
stir it into chestnut puree with remaining
rum.
Whip
cream until just thick, and fold half into chestnut
mixture.
Sandwich cake layers with some of chestnut mixture
and transfer to a serving plate. Pipe or spread
remaining chestnut mixture around and on top of
sponge cakes.
Put
remaining cream in a piping bag fitted with a small
star nozzle. Decorate top of dessert with a large
swirl or cream pipe small rosettes around base.