Frozen Custard
2 1/2 cups milk 2 teaspoons cornstarch 2 eggs 1/2 cup sugar 1 teaspoon vanilla Heat one and one-half cups of the milk in a double boiler. Stir into it the cornstarch stirred smooth with a little cold milk. Then add the yolks and whites of the eggs, beaten separately, first diluting the yolks with some of the hot milk. Remove from the fire, and stir in the sugar and vanilla. Let the custard cool, then pour in the rest of the milk, or part of it may be cream. Freeze.
A plain boiled custard, thinned and frozen — the ancestor of what American shops still sell as frozen custard. The whole recipe hinges on cooking the egg mixture gently enough that it thickens without curdling.
- Custard temperatureHold the double boiler water at a bare simmer and cook the egg mixture until it reaches 175-180F and coats a spoon. Above about 185F it will scramble, and no amount of beating afterwards will make it smooth again.
- The cornstarch slurryStir the cornstarch into two or three tablespoons of cold milk until there are no lumps before it goes into the hot milk. The starch here is insurance: it stabilises the eggs and lets the custard tolerate a little more heat than a pure custard would.
- Beaten separatelyBeating yolks and whites apart appears in many recipes of this period and adds a little lightness. Temper the yolks with hot milk as directed, then add the beaten whites, working gently; most of that air is lost during freezing anyway, so skipping the separation costs little.
- Sugar off the fireAdding the sugar after cooking is worth keeping; sugar stirred in at the end dissolves in the residual heat, and keeping it out of the pan does not slow the custard's thickening.
- Strain and chillPass the cooked custard through a fine sieve to catch any set egg, then chill it thoroughly — several hours or overnight. A cold mix freezes faster and finer-grained than a merely cool one.
- "Freeze"The original assumes a hand-cranked bucket freezer packed with crushed ice and coarse salt; period books vary in the proportion, anywhere from about one part salt to three of ice to one in eight, with cranking usually taking twenty to thirty minutes. In an electric ice cream machine, churn 20-25 minutes, then firm the custard in the freezer for two hours before serving.
- Cream optionThe recipe allows part of the final cold milk to be cream. All milk gives a lean, icy result; using cream for some of that last cup gives something much closer to modern frozen custard.
- YieldAbout a quart, serving four to six. It is best eaten the day it is made — with only 1/2 cup sugar and nothing but the two teaspoons of cornstarch to help, it hardens considerably after a day in the freezer.