Step 1

Heat the milk and the vanilla pod and seeds in a pan over a medium heat, stirring frequently, until just coming up to boiling. Set aside for 15 minutes to infuse and cool slightly.

Step 2

Mix together the egg yolks, sugar and cornflour in a heatproof bowl stirring to get a smooth paste.

Step 3

Slowly pour the hot milk into the paste, stirring constantly until completely combined.

Step 4

Strain the mixture into a clean saucepan and, stirring constantly, cook gently over a low heat until the custard thickens. This happens at around 75C/165F, if you have a cooking thermometer. If you don't, coat the back of the spoon with custard and draw a line through with your finger. If the line holds, the custard is ready.