Whisk together the milk, custard powder, sugar and salt in a saucepan.
Bring it to cook on low flame, stirring occasionally to avoid sticking at the bottom of the pan, till the mixture thickens.
Switch off and allow to cool slightly.
Meanwhile, prepare the jelly as per pack instructions.
Keep 6 serving portions (around 200 ml) ready.
Divide the jelly equally between all the cups.
Pour the slightly cooled custard equally into all the cups, you will see it going and settling at the bottom.
Cover with cling film and allow it to set in the fridge for around 4 hours.
Serve cold as is or with a dash of whipping cream!