Set aside 8 of the sponge finger biscuits.
Roughly chop the remaining sponge finger biscuits and divide half between 8 individual serving glasses or bowls.
Drizzle half of the espresso coffee over the top of the biscuits allowing it to soak in.
Whip the thickened cream, Kahlua, caster sugar and mascarpone using hand-held beaters or a stand mixer until soft peaks form.
Divide half of cream mixture over the top of the sponge finger biscuits in the serving glasses.
Place the 8 remaining sponge finger biscuits gently into the serving glasses (refer to images).
Sprinkle the remaining chopped sponge finger biscuits over the cream.
Drizzle over the remaining espresso coffee.
Divide the remaining cream mixture between the serving glasses.
Top with grated chocolate.
Refrigerate for at least 3 hours (overnight is best) and serve.