Cut the chocolate finely and set aside.
In a saucepan, bring the cream to a boil and remove from heat. Add the chocolate and let stand a few minutes; whisk smooth and pour into a large bowl. Whisk in the liqueur and cool to room temperature.
In a mixing bowl, combine egg whites and sugar and place over a pan of simmering water, whisking constantly, until egg whites are hot and sugar is dissolved. Whip on mixer until cooled and risen in volume - do not overbeat until egg whites are dry.
Fold meringue into chocolate mixture, and place in bowls or glasses. Garnish with chocolate shavings just before serving.