Custard is not really all that tricky but it does need to be cooked carefully. It is worthwhile mastering the technique because not only is the flavor of homemade custard much richer than that made with powder, but rich, smooth custard is the base on which many other desserts are built. For instance, it is essential for a superior trifle; when set with gelatin it turns into a bavarois; and frozen, it is the foundation of the very finest ice cream.
The most important thing when making custard is to cook it very gently and slowly. Trying to cook it in a rush is a mistake as it will almost invariably curdle. It must take its time and must never boil, so the choice of pan is important. For best results, dessert chefs cook custard in a bain-marie, or water bath, which is a pan of simmering water large enough to hold smaller pans. This makes it easier to control the temperature of delicate mixtures such as custard. A bain-marie is easy to improvise. Alternatively, make the custard in the top of a double boiler, or in a heavy-based pan on a very gentle heat. In addition, the custard must be stirred continuously while it is being cooked so that hot patches do not form against the side of the pan.
Custard is traditionally flavored with vanilla. You can either infuse the milk with a split vanilla pod or add a few drops of vanilla essence. It does not have to be vanilla, however; try other flavorings, such as almond, nutmeg or mixed spice.
Once the custard has thickened, (it will never thicken as much as packet custard) take it off the heat and transfer it to a cold jug or bowl, so it does not continue cooking. Serve it immediately if you want it hot. To serve it cold, cover the surface of the custard to prevent a skin from forming on the top, leave to cool completely, then refrigerate.
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