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Sponge Rusks
Cut a stale spongecake in finger-lengths, and brown them on both sides in the oven. When crisp, put them in a tin canister, and keep in a dry place.
A two-line method with one variable that decides everything: the cake must be dry before it goes in, and the oven must be low enough to dry rather than colour it.
- Oven temperatureThe recipe gives none. A low oven, in the region of 275-300F, will crisp the fingers through to the centre rather than merely colouring the outside, though the original does ask for them to be browned on both sides. Expect it to take a good while, turning them partway, and judge by crispness rather than by the clock.
- "Stale" is a requirement, not a convenienceA fresh sponge is too moist and too tender to slice cleanly, and it will steam and go leathery instead of crisping. Day-old or two-day-old cake cuts into neat fingers and dries evenly.
- CuttingThe recipe gives no dimensions. "Finger-lengths" is usually read as something around 3 inches long and about 3/4 inch thick. Thicker pieces stay soft in the middle; much thinner and they scorch before they dry.
- Testing for doneThey firm up as they cool, so judge by snapping one after a minute out of the oven rather than by feel while hot. Any give in the centre means more time at low heat.
- The tin canisterA close-fitting tin, kept in a dry place as the recipe directs, is the point of the instruction, and it still is. Cool the rusks completely first, or trapped steam will soften the batch overnight.
- Yield and useYield depends entirely on the size of the cake, which the recipe does not state. Rusks of this kind were commonly served with tea, and with wine or milk for invalids and children.
Rusks are baked twice — dried out after the first baking — the same idea as Italian biscotti and German Zwieback, both of which do literally mean "twice-baked"; the technique long predates any of those names, since drying a baked good out was the ordinary way of making it keep before airtight packaging. A recipe like this one belongs to the older household economy of using things up: the leftover end of a sponge cake, too dry to serve as cake, becomes a stable store-cupboard item. Nineteenth-century cookery books also place rusks squarely in the sickroom and nursery, where a dry, plain, easily soaked biscuit was considered suitable for weak digestions and teething infants.