Frangipani Cream

A stirred custard flavoured with lemon butter and crumbled almond macaroons — the dessert equivalent of a pastry cream, meant to be spooned cold from glasses or used to fill a shell.

• The hinge: keep the custard below a simmerFour whole eggs in two cups of milk sets at roughly 175-180F, and the water in the lower pan should stay hot but never boiling. Stir constantly and pull it off the heat the moment it coats the spoon; a boiled egg custard curdles and cannot be brought back.
• Macaroons meant almondMacaroons here most likely meant almond -- given the title, the macaroon intended is probably a crisp almond biscuit of the amaretti type rather than a coconut one (though coconut macaroons were also common in American books of the period) and not a French macaron. Almond is what makes the dish frangipane; coconut will taste like a different dessert entirely.
• Lemon rind in butterMelt the butter, add the finely grated zest, and warm it a minute or two without browning to draw the oils out. Stir it into the finished custard off the heat, as the recipe directs.
• Whole eggs, and how thick it will beFour whole eggs give a soft pouring custard rather than a spoonable cream. If you want it firm enough to hold a shape, use six yolks in place of the whole eggs; the recipe as written is intended to be loose.
• Crumb textureFold the crushed macaroons in just before chilling if you want them to keep some crispness, or an hour ahead if you would rather they dissolve into the cream.
• ChillingCover the surface with film touching the custard to stop a skin forming, and give it at least three hours in the refrigerator. Serve within two days.
• YieldAbout three cups, which is four to six small glasses, or enough to fill a nine-inch baked tart shell.