1 ounce green crème de menthe
1 ounce white crème de cacao
1 ounce heavy cream
Shake well with ice and strain into a cocktail glass.
Source: Philibert Guichet Jr. - Tujague's, New Orleans

This cocktail was apparently created by Philibert Guichet Jr., the owner of Tujaque's bar in New Orleans. As the story goes, it was submitted as an entry to a New York cocktail contest which was held, amazingly enough, in 1928 just before Prohibition was repealed. It is reported to have won second place. (Source: Roy F. Guste, Jr. "The Restaurants of New Orleans") Some other sources refer to the contest happening in 1919 however, just prior to Prohibition. However since one of the reported judges was Walter Winchell, who's career didn't really start until 1920, it is more likely that the contest happened during Prohibition.