It really is easy to prepare:
1. Measure a pint of milk and put it in a pan to boil.
2. Place 2 tablespoons of custard powder and 1 to 2 tablespoons of sugar into a jug, using a little of the milk that is warming, make a smooth paste.
(You can, of course, also make the custard in a microwave, but do remember to stop and stir it to prevent lumps. Also keep a close eye as it can quickly over cook and become too thick! )