Cook ½ pound of prunes until soft; remove the stones and cut the prunes into small pieces. Mix with some chopped nuts and the yolks of 3 eggs well beaten with 3 tablespoonfuls of pulverized sugar. Add 1 teaspoonful of vanilla and the whites of the eggs beaten stiff. Put in a pudding-dish and bake in a moderate oven for ten minutes and serve.
A very short list of ingredients and an even shorter bake time, which is the one thing here that needs adjusting. Read the original as a base recipe and give it the oven time a soufflé actually requires.
- Moderate oven350F. If you are baking in a shallow dish rather than a deep one, 375F gives better lift.
- Ten minutes is not enoughTen minutes looks short -- half a pound of fruit plus three eggs may still be loose in the centre after ten minutes at 350F. Allow 20-25 minutes in a buttered 1-quart dish, until puffed and just set with a faint wobble; a shallow gratin dish may be closer to 12-15.
- Pulverized sugarFiner than granulated and closer to what is now sold as superfine or caster. Confectioners' sugar works, though its cornstarch makes the mixture slightly denser.
- The prunesThe half pound is presumably weighed with the stones in, since the recipe has you remove them after cooking; that leaves roughly 6-7 oz of fruit once pitted. Modern pitted prunes are already soft: 10 minutes' simmer, or a soak in hot water, is plenty. Drain them well or the whites will collapse.
- Chopped nutsNo quantity is given. About 1/3 cup of walnuts or almonds is in proportion; more than half a cup weighs the batter down.
- FoldingBeat the whites to soft-firm peaks, not dry, and fold them into the prune and yolk mixture in two or three additions. This is the whole structure of the dish, as there is no flour or starch to hold it.
- Dish preparationButter the dish and dust it with sugar. The original says only "a pudding-dish," meaning an ovenproof baking dish.
- Yield and servingServes about four. Serve straight from the oven; a flourless fruit souffle sinks within a few minutes and does not reheat well.
Prunes were one of the great standbys of the turn-of-the-century pantry: dried, cheap, shelf-stable, and sweet enough to carry a dessert without much sugar. Perhaps that is part of why a book organised as a dish a day can place a French dessert in mid-June, when little fresh fruit was yet in season. The technique is the plain end of the French repertoire, a soufflé aux pruneaux built on beaten whites alone rather than on the flour-thickened pastry-cream base of a restaurant soufflé, and it belongs to the same family of egg-lightened fruit puddings that English and American cooks knew as fruit whips or snows. Books of this kind, which offered a different national dish for every day of the year, were part of a broader vogue for cosmopolitan home cooking; the recipes are usually simplified well past what a French kitchen would recognise, and the label "French" here signals ambition more than provenance.