Directions

1. Put the milk and cream in a saucepan. Slit the vanilla pod down its length with a small, sharp knife and scoop out as many of the tiny black seeds as you can into the milk mixture. Add the pod to the pan, too. Heat the whole lot over a low heat, stirring occasionally, until it almost boils - you'll see a few bubbles at the edge. Take off the heat and set aside for 30 mins so that the vanilla can infuse.
2. Mix the egg yolks and sugar together in a bowl. Gradually pour the milk over the egg mixture, whisking continuously until combined. Pour everything back into the cleaned pan, return to a low heat and cook for 8-10 mins, stirring all the time with a wooden spoon, until the custard is thick enough to coat the back of the spoon. Make sure it doesn't boil or you will end up with scrambled eggs.
3. Pour the custard through a fine sieve into a bowl, then sit it in a bigger bowl, one-third full of ice and water, to cool it down - keep stirring every now and then to stop a skin forming. Chill to make sure it is completely cold, putting cling film directly on the surface of the custard to prevent a skin from forming.
4. Pour the custard into an ice-cream machine. Churn following manufacturers' instructions until frozen, then spoon into a metal or plastic freezer-proof container. Cover and freeze until solid. If you don't have an ice-cream machine, pour the custard into the container and freeze. Every 2-3 hrs, take the mixture out of the freezer and give it a stir. Once it is softly set, beat it well with electric beaters, then freeze solid. It will keep in the freezer for 3 months. Remove from the freezer 15 mins before serving to allow it to get soft enough to scoop.