Nesselrode Pudding with Candied Chestnuts

Ranhofer writes for a kitchen with cross-references at hand and a salt-and-ice freezer in the corner; the assembly itself is straightforward once you know what each numbered component was.

• The hinge: work fast and coldEverything must be at soft-scoopable temperature and go into a mold that has been chilled hard. The vanilla lining will slump into the chestnut filling if either is loose, and the layers lose definition. Chill the mold in the freezer for an hour before you start, and return the assembly to the freezer between layers if it softens.
• Italian meringueRanhofer's No. 140 is egg whites whipped with hot sugar syrup, cooked to roughly the soft-ball stage, poured in a thread. It lightens the chestnut ice and keeps it from setting hard. The recipe says only "a quarter as much," without saying whether that is by volume or by weight.
• Chestnut ice creamHis base appears to be a custard with sweetened chestnut puree. Unsweetened chestnut puree sold in cans, or crème de marrons with the sugar in the custard reduced accordingly, both work; roasted and peeled fresh chestnuts pushed through a sieve are closest to the original.
• Candied chestnutsMarrons glacés, sold whole in syrup or individually wrapped. Break rather than chop them so the pieces stay irregular, and drain syrupy ones well or they will freeze into hard sweet nuggets.
• MaraschinoIn 1894 this meant maraschino liqueur, a clear dry cherry-pit spirit, not the syrup from a jar of bright red cherries. Luxardo or a similar Dalmatian-style bottling is the right thing. Keep it to a few tablespoons across the whole mold: alcohol depresses the freezing point and too much leaves the pudding slack.
• Freezing timeAn hour and a half in a packed ice-and-salt cave is a much harder chill than an hour and a half in a domestic freezer. Give a filled two-quart mold at least six hours, and overnight is better.
• UnmoldingDip the sealed mold in warm water for five to ten seconds, wipe it, and turn out onto a chilled platter. The napkin Ranhofer dresses it on presumably kept the pudding from sliding and absorbed melt; a folded linen napkin on the serving dish still does both.
• The sauceVanilla ice cream slackened with whipped cream and maraschino, essentially a cold pouring sauce. Make it just before serving and keep it in a chilled jug; it will separate if it sits.
• YieldA full two-quart mold will serve roughly twelve to sixteen if cut in slices rather than scooped; the recipe itself states no yield.