Ingredients

1. Pour the milk into a small pan and bring to the boil. Whisk the egg yolks and sugar in a bowl, then whisk in the milk. Return the mixture to the pan and heat gently until you have a thin pouring custard that coats the back of the spoon, taking care not to overheat it. Pour it straight away through a sieve into a clean bowl, stir in the vanilla, cover the surface with clingfilm and leave to cool, then chill.
2. Using an electric whisk, whip the double cream until it forms soft fluffy peaks and fold it into the custard. Coarsely grate the chocolate.
3. If using an ice-cream maker, freeze according to manufacturer’s instructions, scattering over the grated chocolate a few minutes before the end. Eat straight away, or transfer to a container, cover and freeze until required.
4. Alternatively, use a food processor. First pour the ice-cream mixture into a container, seal and freeze until softly frozen (start checking after about 3 hours, and hourly thereafter). Scoop the soft ice cream into the bowl of a food processor and whiz to a thick slush. Spoon back into the container, scatter over and fold in the grated chocolate, seal and return it to the freezer for another few hours or overnight.