Boiled Custard
It is considered better made of the yolks only of the eggs, some whites may be used, however. A dessert spoonful of sugar is enough for each egg, and five yolks are quite sufficient for a quart of milk. Beat the yolks and the sugar together to a froth and stir in the milk; put it into a double boiler. Stir the mixture constantly until it is a little thickened. If it is well stirred, the custard will be a smooth cream; if allowed to remain a few moments too long in the boiling water after it begins to thicken, it will curdle and be spoiled.
This is crème anglaise under an older name, and the whole recipe hangs on knowing when to stop. A thermometer removes the guesswork the original had to describe in prose.
- The hinge: 175-180FPull the custard the moment it coats the back of a spoon and leaves a clear track when you draw a finger through it, around 175-180F on an instant-read thermometer. Egg yolk proteins set from roughly 150F and curdle above about 185F, which is exactly the "few moments too long" the author warns of.
- A dessert spoonfulA dessertspoon sits between a teaspoon and a tablespoon, roughly 2 teaspoons. Five yolks therefore take about 3 1/3 tablespoons of sugar per quart of milk, which is a restrained, old-fashioned sweetness by modern standards.
- Ratio and bodyFive yolks to a quart of milk gives a thin pouring sauce. For something that clings to a pudding or a slice of cake, use eight to ten yolks per quart, or replace a cup of the milk with cream.
- WhitesThe whites add setting power but also a faintly sulphurous flavour and a tendency to curdle sooner, which is why yolks alone are "considered better." If you use whole eggs, keep the heat lower still.
- Double boilerKeep the water in the lower pan hot but not at a rolling boil, and do not let the upper pan touch the water. A heavy saucepan over low direct heat works faster if you stir continuously and are watching the thermometer.
- Scald the milk firstHeating the milk before it meets the eggs, then adding it to the yolks in a slow stream while whisking, shortens the cooking time and many cooks find it gives a smoother result. The recipe as printed does not say whether the milk goes in warm or cold.
- Strain and flavourPour the finished custard through a fine sieve into a cold bowl to catch any threads of set egg, and stir in a teaspoon or two of vanilla off the heat. The recipe as printed calls for no flavouring at all; nutmeg, lemon zest and a spoonful of sherry are all common in period custard recipes.
- Yield and keepingAbout a quart, enough sauce for eight servings. Cool it quickly, cover, and refrigerate no more than three days; it will thin slightly on standing and can be whisked smooth again.
"Boiled custard" is a misnomer of long standing, and the recipe itself admits as much by insisting on a double boiler and warning that boiling water will spoil the mixture. The name most likely distinguished it from baked custard, which went into the oven in a dish, rather than describing what the cook was meant to do. As a stirred sauce of yolks, sugar and milk it is the same preparation French kitchens called creme anglaise, and much of the period's dessert repertoire depended on it: poured over cottage pudding and steamed puddings, layered into trifle, frozen into ice cream, or served in cups on its own. In the American South boiled custard survived as a drink in its own right, thinned with more milk and served cold at Christmas, and it is still sold that way in parts of Tennessee and Kentucky.