Place the chocolate into a heatproof bowl over a pan of simmering water and melt it, taking care not to let the chocolate over heat.
Meanwhile, whisk the egg whites until they form soft peaks.
Stir the liqueur into the beaten egg yolks and add to the melted chocolate.
Pour the chocolate mixture into the egg whites and gently fold together.
Divide evenly between four ramekins and transfer to the refrigerator to chill. Decorate with whipped cream and grated chocolate.