In a saucepan, heat the milk over low heat until it’s warm but not boiling. Remove it from the heat and set it aside.
In a mixing bowl, whisk together the egg yolks, caster sugar, and cornflour until well combined.
Gradually pour the warm milk into the egg mixture, whisking continuously to avoid curdling.
Pour the mixture back into the saucepan and return it to low heat. Cook while stirring constantly until the custard thickens and coats the back of a spoon. This should take about 10-15 minutes.
Remove the saucepan from the heat and stir in the vanilla extract.
Allow the custard to cool to room temperature, then transfer it to the refrigerator to chill for at least 30 minutes before serving.
