Daly's Bartenders' Encyclopedia by Tim Daly (1903, p.85)

0.5 glassBenedictine — benedictinebase
cream — pure creamother
1egg yolk — yolk of one eggother
  1. Half fill a fancy sherry glass with Benedictine and drop in the yolk of one fresh cold egg.
  2. Fill up with pure cream and serve.

Daly's collegiate-strength warning is a useful social gloss for this rich restorative miniature.

The direct-glass cold yolk service is the defining structural point.

See also: Miss Liberty, Sherry Chicken