Today's OED antedating: "custard pie"

Custard pie, gooey allusive symbol of slapstick comedy, for which it is a celebrated prop ("custard," sec 2 (b), first use cited 1933): Essay titled "The Ostermoor School of Drama," by Heywood Broun, Vanity Fair, June 1919, p 53, col 1: "The bed seems to be, to the farce of the moment, what the custard pie was to the early moving pictures—the entire plot."