200 g (7 oz) coarsely grated dark chocolate, plus extra for sprinkling
900 ml (1½ pints) milk
150 ml (¼ pint) double cream
1 tablespoon icing sugar
75 ml (3 fl oz) Irish cream liqueur
1–2 tablespoons caster sugar, according to taste
Place the chocolate in a large heatproof jug. Heat the milk in a pan until it is almost simmering.
Meanwhile, whip the double cream with the icing sugar until it forms soft peaks, then fold in 1 tablespoon of the cream liqueur.
Pour about a quarter of the hot milk into the jug, stirring until the chocolate has melted. Add the remaining milk in a steady stream, stirring constantly. Add the remaining Irish cream and sweeten to taste with the caster sugar.
Pour the hot chocolate into mugs and top with the desired quantity of whipped cream. Sprinkle with a little extra grated chocolate to decorate, and serve immediately.