If you don't have an ice-cream machine, put the mixture in a large freezer-proof container, cover and freeze for 3 hours or until partially frozen. Transfer to a food processor bowl and process until smooth. Return to the container, cover and freeze for 3 hours or until completely set.
400 ml (14 fl oz) milk
300 ml (10 1/2 fl oz) thickened (whipping) cream
250 g (9 oz) dark chocolate, finely chopped
5 egg yolks, at room temperature
110 g (3 3/4 oz/1/2 cup) caster (superfine) sugar
1. Put the milk, cream and chocolate in a medium heavy-based saucepan over low heat and cook, stirring constantly, for 3-5 minutes or until the chocolate melts and the mixture is smooth. Remove from the heat and set aside.
2. Meanwhile, use an electric mixer with a whisk attachment to whisk the egg yolks and sugar in a medium mixing bowl for 5 minutes or until very thick and pale.
3. Add the egg mixture to the chocolate mixture. Use a wooden spoon to stir constantly over medium-low heat for about 5 minutes or until the custard thickens slightly, coats the back of the spoon and holds its shape when you draw your finger across the spoon. Transfer the custard to a bowl and place in the freezer, stirring occasionally, until well chilled but not set.
4. Churn the chilled chocolate mixture in an ice-cream machine following the manufacturer's instructions. Transfer to a freezer-proof container and freeze for 3-4 hours, until firm. Serve in scoops.