If using vanilla bean pod, split the pod and scrape out all the seeds. Place the seeds and pod into a small pot, along with 20g of the sugar, milk and a pinch of salt and set over low heat, stir occasionally to melt the sugar. If using vanilla bean paste or essence, just add that into the small pot with the sugar, milk and salt.
Whisk the yolks and the rest of the sugar until pale and creamy.
Bring the milk to a boil and immediately remove from heat. Slowly trickle into the yolks while whisking, until fully incorporated.
Return the mixture to the small pot and place over low heat, constantly stir either with the whisk or spatula, until the sauce slightly thickens enough to coat the back of a spoon, roughly 1-3mins. If you are concerned about the eggs, take the temperature to 83C to pasteurise it.
The creme anglaise is now ready. If you would like a richer, creamier sauce, you can add in the 1/2 cup of cream. Taste and adjust the sweetness if needed, I would add another 10g of sugar, if using the cream.