Set aside 1 glass of cold milk.
Pour the rest of the milk into a saucepan. Add the split vanilla pods.
Bring to the boil.
Put the sugar, flour and egg yolks in the bowl with the metal blade. Pulse twice, add the glass of milk via the feed tube and pulse twice again.
Remove the vanilla pods from the hot milk. Scrape the seeds from the interior with the tip of a knife and add them to the milk.
With the machine running, immediately start pouring the milk very gradually onto the preparation.
Return everything to the saucepan and simmer gently, stirring with a wooden spatula.
Remove from the heat as soon as the cream starts to coat the spatula.
Pour into a large bowl, sprinkle with caster sugar to prevent a skin forming and leave to cool.
You can use this cream to fill pastry puffs or eclairs.