The standard test is to cook until mixture will “coat the back of a metal spoon,” not as easy to determine as it sounds because uncooked custard will also leave a film on a spoon. The difference is that cooked custard should leave a thick, translucent, almost jellylike coat about the consistency of gravy. If you suspect that custard is on the verge of curdling, plunge pan into ice water to stop cooking.
Insert a table knife into custard midway between rim and center (not in the middle as cookbooks once instructed). If knife comes out clean, custard is done. Remove at once from water bath and cool. To chill quickly, set custard in ice water-but only if baking dish is one that can take abrupt changes of temperature without breaking.
What to Do About Curdled Custard:
If it’s baked custard, the best idea is to turn it into a Trifle by mixing with small hunks of cake if stirred custard, strain out the lumps and serve as a sauce over cake, fruit, or gelatin dessert.
Keep custards refrigerated; they spoil easily, often without giving a clue.
Keywords: Information, Puddings and Custard, French, Custard, Eggs, Dairy, Vanilla