No. 615

Mayonnaise Mousseline Sauce

Sauce Mayonnaise Mousseline

Made with a jelly mayonnaise the same as explained in No. 613, leaving out the chervil, and stirring in the same quantity of unsweetened whipped cream, well drained and very firm. An ordinary mayonnaise without being jellied can also be used.

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For the Modern Kitchen

Ranhofer writes in shorthand, assuming you have No. 613 open beside you: this is a mayonnaise lightened with an equal volume of whipped cream. The whole thing succeeds or fails on how firm and how dry that cream is.

Drain the cream properlyWhip heavy cream to firm peaks, then let it sit in a fine sieve over a bowl for 10-15 minutes and discard the liquid that weeps out. Loose or watery cream will thin the mayonnaise and break it within the hour.
Equal quantities, by volume"The same quantity" means as much whipped cream as you have mayonnaise. One cup of mayonnaise to one cup of whipped cream gives a pale, barely tart sauce; halving the cream keeps more mayonnaise character.
Fold, do not stirDespite the wording, treat this as a folding job with a spatula in three additions. Stirring knocks the air out and you lose the mousseline texture that is the entire point.
Jellied mayonnaiseNo. 613 is not reproduced here, but the phrase 'jelly mayonnaise' points to a mayonnaise set with aspic or gelatin, which is what would let the sauce hold a shape on cold fish, chicken or vegetables. If you use gelatin, work quickly and keep everything cold, since the sauce sets as it chills. The unjellied version Ranhofer permits is a spoonable dressing rather than a coating.
Unsweetened, and mean itModern cartons of whipping cream are sometimes pre-sweetened or stabilized. Read the label; sugar or vanilla in the cream turns this into something quite different.
ChervilRanhofer simply directs that it be left out and gives no reason. If you want an herb, a very small amount of chive or tarragon folded in at the end stays close to the spirit of the sauce.
Raw yolksAny classic mayonnaise made at home relies on uncooked egg yolk. Pasteurized shell eggs or pasteurized yolk are the sensible choice if you are serving the very young, the elderly, or anyone pregnant or immunocompromised.
Holding and yieldKeep it refrigerated and use it the day it is made; the cream deflates and weeps after several hours. Ranhofer gives no yield; as a rough guide, about two cups of finished sauce will dress cold poached salmon or chicken for six to eight.

A Little History

Mousseline in French kitchen usage is generally taken to evoke the lightness of muslin, and it was applied to sauces lightened with whipped cream — most familiarly hollandaise, of which this is the cold counterpart. Charles Ranhofer, chef at Delmonico's in New York and author of The Epicurean (1894), places it among a run of mayonnaise variations built one on top of another, each recipe pointing back to the last, which is how professional manuals of the period were organized: the reader was assumed to be a cook working through a numbered system, not a householder reading a single page. The jellied form belongs to the great age of cold buffet cookery, when chaud-froid and aspic-set sauces were brushed over poached fish, boned poultry and mousses so they would hold a smooth, opaque surface for hours on a display table.