White chocolate truffle torte
Line the sides of a 20cm springform tin with a tall strip of non-stick baking paper. Place 1 sponge, base-side up, in the bottom of the tin and sprinkle over 3 tablespoons of the orange-flavoured liqueur. Remove the chocolate mixture from the fridge and pour evenly on top of the sponge. Freeze for 1 hour to firm up the filling. Sprinkle the remaining liqueur over the base of the second sponge and place base-side down on top of the truffle mixture. Wrap the tin well in cling film and freeze overnight or for up to 1 month.
For the curls, put a baking sheet in the fridge to chill. Meanwhile, put the remaining chocolate into a bowl over a pan of just-simmering water. Leave until melted, remove from the heat and gently stir until smooth. Pour onto the chilled baking sheet, spreading very thinly with a palette knife. Chill until set but not rock hard. Hold a fish slice at a 45-degree angle to the chocolate and scrape along and away from you to make lots of short curls.
Transfer the torte to the fridge, 2 hours before serving, until soft enough to slice yet firm. Remove from the tin, cover with a thick layer of chocolate curls, then dust with icing sugar. Cut into wedges to serve.