No. 570

Cambridge Butter

Beurre Cambridge.

Lay in a mortar and pound well, six hard boiled egg-yolks, with four well cleansed anchovies and a spoonful of chopped capers, also some tarragon and chives; when the whole is reduced to a paste, add to it one spoonful of English mustard, and the same quantity of French mustard, some salt, pepper, and vinegar, and one pound of fresh butter. Rub the compound through a sieve, and then mix in with it a tablespoonful of chopped parsley.

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For the Modern Kitchen

A cold compound butter in the classic garde-manger style — essentially Cambridge sauce worked into a pound of butter instead of oil. It keeps for weeks and is meant to be sliced onto hot food or spread for canapés.

The hinge: keep everything cold, and the butter softThe butter should be pliable at cool room temperature, never melted or oiled off, or the paste will separate when it chills. Pound or process the yolks, anchovy, capers and herbs to a smooth paste first, then work the butter in.
"A spoonful" is not a measurementRanhofer uses spoonful loosely, and note that he specifies a "tablespoonful" for the parsley, so the two need not be the same measure. For a pound of butter, a tablespoon each of the two mustards and about 2 teaspoons of vinegar is a reasonable starting point; taste and adjust.
English vs. French mustardEnglish mustard means the fierce prepared kind (Colman's, or dry powder slaked with water and rested ten minutes); French mustard in this period would generally have meant a Dijon-style mustard. Using two of the same defeats the point — one brings heat, the other acidity and body.
"Well cleansed anchovies"The phrase most likely points to whole salt-packed anchovies, which must be rinsed, filleted and boned. Four oil-packed fillets, blotted, are the nearest modern stand-in; four whole salted fish would give roughly twice as much anchovy, and considerably more salt.
Salt last, if at allAnchovies, capers and prepared mustard all carry salt. Taste the finished paste before adding any, and remember cold butter tastes less salty than it will on hot meat.
The sieveRubbing through a fine sieve with a wooden spoon or plastic scraper removes anchovy fibre and yolk grain and is what gives the butter its gloss. A food processor gets close but not all the way; sieve anyway if it is going on a plate cold.
HerbsFresh tarragon and chives only — dried tarragon turns hay-like in raw butter. Figure a tablespoon of each, chopped, and keep the parsley for the end as directed so it stays green and distinct.
Yield and useAbout 1 1/4 lb, enough for 30 to 40 servings. Roll in parchment into logs, chill firm, and slice coins onto grilled steak, lamb chops, or broiled or poached fish; it also spreads well on toast for cold hors d'oeuvre. Refrigerate a week, freeze three months.

A Little History

Cambridge butter is the compound-butter form of sauce Cambridge, a cold English preparation of pounded hard-boiled yolks, anchovy, capers, mustard and green herbs that circulated through nineteenth-century professional kitchens and was later codified by Escoffier as an oil-mounted sauce for cold meats. Its name is generally traced to the university town rather than to any documented creator, and it belongs to the same family of assertive cold anchovy-and-mustard relishes the English kept for cold beef and boiled fish. Charles Ranhofer, who ran the kitchens at Delmonico's in New York and published The Epicurean in 1894, files it among a long run of flavored butters — anchovy, cayenne, ravigote, montpellier. The mortar and the sieve are the tell that this is pre-blender work, done by an apprentice with time on his hands.