Brake the chocolate into pieces, then place in a heavy-based saucepan with the milk.
Heat gently, stirring, until smooth, then remove from the heat to cool slightly.
Beat the sugar and egg yolks in a bowl until pale and thick. Stir in the cooled chocolate milk, then strain back into the pan.
Cook the custard over a gentle heat, stirring all the time, until it thickens and coats the back of a wooden spoon. Don’t allow the mixture boil or it will curdle.
Pour into a bowl and leave to cool, stirring occasionally.
Once cooled, whip the cream into soft peaks, and fold through the chocolate mixture.
Churn in an ice cream machine, according to the manufacturer’s instructions, until it’s frozen.
