4 tsp sugar (I used raw sugar but can use caster if you prefer)
Approx 1 litre milk
splash of vanilla extract (optional)
Whisk together the custard powder and sugar in a saucepan
Add small amount of milk and whisk to get a paste like consistency with no lumps
Add rest of milk and whisk until no lumps.
Heat over the stove on a medium to low heat. Keep whisking until the mixture thickens and is creamy. Do not let it bubble or burn on the bottom of the pan. If you suspect it has burnt stop mixing and move the mixture to another saucepan. You don’t want the burnt bits to go through your custard.