Melt the dark chocolate with the Amaretto in a heatproof bowl set over a saucepan of simmering water, stirring until well combined. Add the butter, and stir until it has melted.
Stir in the icing sugar and ground almonds.
Leave the mixture in a cool place until firm enough to roll into 24 balls.
Put the grated chocolate on a plate and roll the truffles in the chocolate to coat them. Put the truffles in paper cases, and chill.