Custard Sauce (Pint milk yolks eggs cupful)

A bare-bones crème anglaise: the whole method rests on stopping the moment it thickens. Four sentences of instruction assume a cook who already knows what curdled custard looks like.

• The hinge: heat controlCook over barely simmering water in a double boiler, or over the lowest direct flame with constant stirring. The sauce is done at 170-180F, when it coats the back of a spoon and a drawn finger leaves a clean track; past about 185F the yolks scramble.
• Temper the yolksWhisk the yolks and sugar together, then pour in the hot milk in a thin stream while whisking before returning everything to the pan. Dumping cold yolks into hot milk is the usual cause of failure here.
• Rescue and insuranceHave a bowl and fine sieve ready. Straining the finished sauce catches any chalazae and the first specks of overcooked egg; if it begins to break, pull it off the heat at once and whisk hard in a cold bowl.
• FlavouringThe original gives none. Infuse a split vanilla pod or a strip of zest in the milk and strain it out, or stir in extract off the heat.
• SugarHalf a cupful is about 100 g, on the modest side for a pint of milk, which suggests a sauce meant to accompany an already sweet pudding rather than stand alone.
• MilkA pint of whole milk gives a pouring sauce. Replacing a quarter of it with cream produces something closer to the thick modern crème anglaise served with steamed puddings.
• Yield and keepingAbout 2 1/2 cups, enough for six to eight servings. Cool quickly, cover the surface to stop a skin forming, and refrigerate no more than two days; it can be served warm or cold but should not be reheated over direct heat.