In a bowl, mix 2 tablespoons of Foster Clark's custard powder with 1-2 tablespoons of sugar.
Gradually add 500ml of cold milk to the custard powder mixture, stirring continuously to avoid lumps.
Heat the remaining 500ml of milk in a saucepan until it almost boils.
Pour the hot milk into the custard mixture while stirring constantly.
Transfer the entire mixture back into the saucepan.
Cook over medium heat, stirring continuously, until the custard thickens.
Once thickened, remove the saucepan from heat.
Allow the custard to cool for a few minutes before serving.
Optionally, add vanilla essence for flavor.
Serve the Foster Clark's custard warm or chilled, as desired.