Take 1 ¾ cups of milk in a saucepan and bring to boil.
Meantime, take remaining ¼ cup milk in a small bowl, add custard powder, make a lump free paste and keep the paste aside.
Once milk comes to a boil, reduce the flame, add custard paste to boiled milk and stir constantly to make a smooth lump free custard.
Cook for a few more minutes until custard coats the back of the spoon.
Add vanilla extract and 3 tablespoon of sugar.
Keep stirring until sugar melts and custard is thick. Keep in mind, custard thickens after cooling.
Turn of the flame, sprinkle remaining sugar on custard and keep aside to cool. Sugar will melt and prevent the custard from forming a thick layer on the surface.