A premium crème de menthe like Marie Brizard's makes this Grasshopper spin-off sing. Bittermens' revolutionary Xocolatl Mole Bitters are worth seeking out. Created by Jackson Cannon of Eastern Standard in Boston.
Fill a stemmed glass with ice and let sit to chill.
In a shaker, combine the ingredients and shake without ice to blend. Add ice and shake until chilled.
Discard the ice from the stemmed glass, shaking out excess water. Strain the contents of the shaker into the chilled glass. Top with bitters.