Melt the chocolate (see
Divide the pieces of vanilla sponge among the chocolate cases. Mix the coffee with the liqueur and spoon over the sponge.
Make the frosting by beating the mascarpone in a bowl with the icing sugar and vanilla extract. Beat in the coffee and cream until evenly combined. Place in a piping bag fitted with a small star nozzle and pipe swirls on top of each case. Scatter with grated chocolate and serve immediately or chill for up to 6 hours.