Fresh Mushroom Patties

This is one of Ranhofer's shorthand entries: it assumes you have already read the béchamel recipe and the patty formula it points to, and it gives no quantities at all. Everything hinges on the egg-yolk liaison, which must not boil.

• The liaison is the whole dishBéchamel thickened with yolks and finished with raw butter will curdle if it reaches a simmer. Temper the yolks with a little hot sauce, return the pan to low heat, and stir until it coats a spoon at around 175-180F, then pull it off and beat in the cold butter.
• Bouchée means the pastry case, not the fillingA bouchée is a small puff-pastry shell — the little sister of the vol-au-vent. Shop-bought puff pastry cut with two rounds, the inner one from a smaller cutter to form the lid ring, bakes at 425F until risen and dry through, roughly 18-20 minutes.
• No. 934 and No. 409The recipe says to finish "exactly the same as for No. 934," the preceding pattern in this run of hot side dishes; Ranhofer does not restate that procedure here, so the filling-and-capping sequence is inferred rather than quoted. No. 409 is the bechamel Ranhofer cites in the text itself; a well-made modern bechamel does the same job.
• Working quantitiesThe original gives none. For 12 small bouchées, figure 12 oz mushrooms, 2 tablespoons butter for frying, about 3/4 cup béchamel, 1/4 cup cream, 2 yolks and 1 tablespoon butter to finish, with a tablespoon of chopped parsley.
• "Fresh" mushrooms was the pointDried and tinned mushrooms were in common use when the book appeared in 1894, so the word may well have carried weight, though how far fresh mushrooms were the exception is not something this page establishes. Cultivated white or cremini mushrooms suit the recipe; cut them in even dice rather than slices so they sit in the case.
• Drive off the water firstFry the mushrooms in butter over fairly high heat until they have given up their liquid and it has evaporated, then let them take a little colour. Mushrooms added wet to a yolk-bound sauce will thin it and the filling will weep in the pastry.
• Assemble at the last minuteFilled cases go soft within a few minutes. Have the shells warm and the filling hot, fill, cap and send them out. This makes an hors d'oeuvre or side for six to twelve, depending on the size of the case.