In a small bowl, combine the cornstarch with 4 tablespoon of the milk. Mix until you achieve a smooth paste without any lumps.
2 tablespoon cornflour/ cornstarch, 500 g whole milk
Place the remaining milk, salt and sugar into a saucepan.
500 g whole milk, 3 tablespoon sugar, 1 pinch salt
Slice the vanilla pod open lengthways and scrape out the vanilla bean pulp. Add both to the milk mixture. Alternatively, mix in the vanilla extract or vanilla sugar.
1 vanilla pod
Bring the milk mixture to a boil. Now remove the vanilla bean from the milk. (Don’t discard, you can use it to make vanilla sugar).
While stirring continuously pour in the starch-milk mixture. Leave to boil for a minute and then remove from the heat.
In a separate bowl, combine 6 tablespoon of the hot milk mixture with the egg yolk and mix until combined. (this is to prevent the egg yolk from starting to cook before it is absorbed by the sauce). Now pour into the rest of the sauce and stir well.
2 egg yolks