Foamy Sauce
1 cup milk 2 tablespoons sugar 1 tablespoon cornstarch 1 small egg white A few grains salt Stir the cornstarch smooth with a little of the milk. Heat the remainder of the milk, with the sugar and salt, to boiling in a double boiler, and stir in the cornstarch. Allow to cook a few minutes, then whip the hot sauce into the stiffly beaten egg white, and return the sauce to the double boiler long enough to cook the white of the egg, stirring constantly. This will cause the egg white to become incorporated with the sauce so that it will not rise to the top after the sauce cools.
A thin cornstarch pudding sauce lightened with cooked egg white — the kind of sauce poured over steamed puddings, baked apples or plain cake. The whole trick is in the last step.
- The hinge: add the egg white off the heatWhip the hot starch sauce into the beaten white in a bowl, not the reverse, then return it to the double boiler. Dropping the white into the pan directly, or letting the mixture reach a hard boil afterward, gives you shreds of cooked albumen instead of an even foam.
- Why a double boilerMilk-and-starch sauces scorch readily over direct heat, and the second cooking is meant to set the egg white gently, well short of a boil. A heatproof bowl over an inch of simmering water does the same job; keep the water below the bowl, not touching it.
- Cook the starch properly"A few minutes" is best read as two to three minutes at a bare simmer after the sauce thickens. Cornstarch tastes raw and chalky if pulled too soon.
- "1 small egg white"Egg sizes were less standardized than today's graded large. Use the white of one medium egg, roughly 1 tablespoon plus 2 teaspoons.
- Beat the white stiff but not dryStiff peaks that still look glossy fold in smoothly. Whites beaten to the point of separating and looking granular will not incorporate evenly.
- FlavoringThe original is deliberately plain, in the manner of an invalid or plain-cooking sauce. A teaspoon of vanilla, a grating of nutmeg or a strip of lemon zest steeped in the milk is period-appropriate; stir extracts in after the sauce comes off the heat.
- Yield and servingMakes a generous cup, enough for four modest servings. Serve warm — it is meant to be poured, and it thickens noticeably as it cools; a splash of hot milk will loosen it.
Cornstarch sauces like this one belong to the era when commercial corn starch, sold in boxes from the 1840s onward, gave home cooks a cheap thickener that needed no eggs and no long reduction. "Foamy sauce" is a loose family name in American cookbooks: some versions are creamed butter and sugar beaten with egg, others — like this one — are a milk sauce lightened with cooked white. The care taken here to keep the white from rising to the top after cooling reflects a period preoccupation with sauces that would hold at the table, and the double boiler and small quantities point toward the plain, easily digested cookery that domestic-science writers of the turn of the century recommended for children, the elderly and the sick.