Prune Puff
4 eggs 1/2 cup powdered sugar 1 cup cooked prunes Whip whites of eggs to stiff froth; add sugar slowly, beating all the time; add prunes which have been stoned and chopped; beat until very light. Put into pudding dish and bake about 10 minutes. Serve cold with soft custard made from yolks of eggs.
Other soft fruits may be used in the same way and the puff may be served hot with sauce or whipped cream.
A four-egg meringue folded around chopped prunes and baked briefly — essentially a fruit-studded soufflé omelette, with the leftover yolks becoming the sauce. Two things are unstated in the original: the oven temperature and how dry the prunes need to be.
- The hinge: dry the prunesCooked prunes hold a great deal of syrup, and any liquid that meets the beaten whites will slacken them and weep in the oven. Drain and blot the stoned prunes, then chop them fine so the pieces stay suspended rather than sinking through the foam.
- Oven temperatureNo heat is given. Bake at 325–350F; the puff should set and take a little color in about 10–12 minutes. Much hotter and the meringue browns and collapses before the center firms.
- "Powdered sugar"In books of this period this usually means finely ground granulated sugar, not the cornstarch-cut confectioners' sugar sold today. Superfine (caster) sugar is the closest match and dissolves cleanly into the whites.
- EggsFour whites go into the puff, four yolks into the custard — the recipe is built to use the whole egg. Whip the whites to stiff but not dry peaks; overbeaten whites break when the prunes are folded in.
- "Pudding dish"The original specifies no size or preparation. A shallow baking dish of roughly 1 to 1 1/2 quarts suits the quantity; buttering is worth doing, since a meringue clings. Do not fill more than two-thirds full.
- The soft custardThe original gives no formula, only 'soft custard made from yolks of eggs.' A stirred custard, not a baked one: the four yolks with roughly 2 cups of milk and 1/4 cup sugar, cooked over low heat or a water bath, stirring, until it coats a spoon -- roughly 175F. It will not thicken much beyond that point, and it curdles above about 185F.
- Expect it to fallServed cold, as directed, the puff will sink and turn dense and chewy near the base. Served hot with sauce or cream it is lighter but must go straight from oven to table.
- YieldNo yield is stated. Four modest servings as written, six if the custard is generous.
The New Royal Cook Book was published by the Royal Baking Powder Company, one of the many free or near-free promotional cookbooks that flour, spice and leavening manufacturers distributed widely in the early twentieth century. Prunes were a staple of that era's American pantry — cheap, shelf-stable, shipped in bulk from California orchards, and heavily promoted as both a dessert fruit and a health food — so they turn up in cakes, puddings, whips and soufflés. "Puff" here belongs to an older family of desserts (puffs, whips, snows, sponges) built on beaten egg white rather than flour, a thrifty way to turn a cup of stewed fruit into something that looks like a company dish. The pairing with a soft custard made from the leftover yolks reflects the same economy: nothing in the egg is wasted.