Corn Pudding (Cups popped corn finely)

This is a baked custard that uses pounded popcorn in place of breadcrumbs or cornmeal. The technique is simple, but the oven and the doneness test are where it goes wrong.

• Slow ovenA slow oven is 300-325F. A custard this thin will curdle and weep if pushed higher, so stay at the low end.
• Water bathThe recipe does not call for one, but setting the buttered dish in a larger pan of hot water reaching halfway up the sides gives a custard this thin a better chance of setting without curdling in a modern oven.
• Doneness"Until firm" means set at the edges with a slight wobble at the centre, roughly 45-60 minutes in a shallow dish, longer in a deep one. A knife inserted an inch from the rim should come out clean. It continues to set as it cools.
• Pounding the cornTwo cups of popped corn is only a small handful of kernels' worth by weight, perhaps half an ounce. A food processor reduces it to coarse meal in seconds; a mortar or a rolling pin and a bag work as well. Unsalted, unbuttered plain popcorn only.
• The soakThe full hour matters. Scalded milk softens the popcorn into something between a crumb pudding and a cornmeal one; shortcut it and you get gritty flecks suspended in custard.
• ScaldingBring the milk just to the point where it steams and shivers at the edges, about 180F, not to a boil. Let it cool below 140F before adding the beaten eggs, or they will scramble.
• Brown sugarPeriod brown sugars were often less refined than modern light brown, though grades varied. Dark brown gives a pronounced molasses note; light brown yields a milder pudding.
• YieldServes five or six as written; the mixture comes to a little over a quart, so a 1.5-quart dish suits it. The recipe directs that it be served with cream or maple syrup, and the pudding is only modestly sweetened on its own.