Biscuit Glace

This is a frozen custard-style dessert built without ever cooking the custard, and that is the problem with it. The notes below explain the wording of the original and why the method cannot be followed today.

• The yolks are never cookedSugar, raw yolks, dissolved gelatine and whipped cream are combined and simply chilled. Nothing in the sequence brings the eggs anywhere near the 160F needed to inactivate Salmonella, and the gelatine liquid is far too small a fraction of the mixture to raise its temperature meaningfully.
• Held a day at low temperatureThe instruction to make it the day before and "set on ice" means the mixture sits for many hours in cooling conditions that, unlike a modern freezer, cannot be relied on to hold food below 40F. Freezing does not kill the organism either; it only pauses it.
• "1/3 box of gelatine"Gelatine was sold in boxes whose contents and weight varied by maker, so this quantity has no reliable modern equivalent. A period box is often taken to have been around one ounce in total, but the fraction cannot be converted with confidence.
• "Set on ice"In this period the phrase covers everything from resting the moulds in a bowl of ice water to burying them in an ice-and-salt pack. Nothing here indicates a hard freeze, and the mixture is served from the glasses rather than turned out.
• "Biscuit" is not a baked elementNo dough or cake is involved. In this family of desserts the word is usually explained as referring to the shape, and to the paper cases such ices were commonly moulded in, rather than to anything baked; this version is simply set in glasses.
• If you want the dishUse a current recipe for a frozen mousse or semifreddo built on a cooked custard base or a hot sugar syrup beaten into the yolks. Do not attempt to patch the method above.