Ubiquitous on old-fashioned desserts, this sauce is basically nothing more than creamed butter that is sweetened and spiked with spirits. One old cookbook calls this “Soft, Hard Sauce.”
Combine the butter, orange zest and confectioners’ sugar in a small bowl and cream together until well incorporated and very light. Stir in the cognac or other spirit and the vanilla.
Spoon the mixture into a glass serving dish or a small bowl; cover with plastic wrap. Chill at least overnight before serving. Or, as Florence B. Jack advises in