Chestnut Pudding with Fruits

An iced moulded dessert from the era before mechanical refrigeration, when a sealed mould buried in ice and salt was the only freezer in the house. The method translates cleanly to a modern freezer, but the quantities need decoding.

• The hinge: set it before the fruit goes in"Thicken this preparation, stirring it on ice" is the step that decides the pudding. Chill the sweetened gelatine and chestnut mixture, stirring, until it thickens to the consistency of soft cream, then fold in the fruit. Add fruit and raisins to a thin mixture and they sink to what will become the top of the turned-out pudding.
• Cheese-mouldA lidded mould whose joints could be closed and sealed, of a shape borrowed from cheese-making; the recipe tells us only that it shuts and has junctures. A charlotte mould, pudding basin or loaf pan lined with plastic wrap does the same job; the lining makes unmoulding far more reliable.
• Ice and salt, and the common pasteRock salt pounded with crushed ice drops the temperature well below freezing point. The "common paste" is a stiff flour-and-water luting paste smeared over the seam to keep brine from seeping in. Neither is needed if you use a freezer, and the paste can be ignored entirely.
• Gelatine leavesGenuinely ambiguous. Nineteenth-century leaf gelatine varied in size and strength between makers, and six of Oscar's leaves are not reliably six modern sheets. Judge by the setting power you need for roughly a quart of mixture and test a spoonful on ice before committing the whole batch.
• Breakfast cupfulA breakfast cup is larger than a teacup, about 8 to 10 fluid ounces. Take it as a generous cup of water, used to dissolve the sugar and bloomed gelatine over gentle heat.
• Half a pound of sugarAbout 1 1/8 cups granulated. If your chestnut purée is already sweetened, this will be cloying; use unsweetened purée, or cut the sugar sharply and taste.
• Chestnut pureeThe recipe assumes plain cooked chestnuts passed through a sieve. Canned unsweetened chestnut purée is the direct equivalent; French crème de marrons is sweetened and already flavoured with vanilla.
• MaraschinoThe clear liqueur distilled from marasca cherries, stones included, not the syrup from a jar of cocktail cherries. Alcohol softens a frozen set, so a few tablespoons is the ceiling, not a starting point.
• Preserved fruitCandied and glacé fruits — cherries, apricots, citron, angelica. Chop small and rinse off surface syrup so the pieces stay distinct rather than bleeding colour into the pale purée.
• Timing and yieldThree-quarters of an hour applies to a mould packed in ice and salt; a domestic freezer needs several hours, and the pudding should be firm to the fingertip through the tin. The recipe gives no yield; a mould of this size would stretch to several servings. Dip briefly in tepid water — seconds, not a soak — before turning out onto a chilled dish.