Not many spirits are surrounded by as much mysticism as green Chartreuse, a potent liqueur made by Carthusian monks in the mountains of France from a secret recipe containing 130 herbs, plants and flowers. Pairing its complex flavors and 110-proof strength with other ingredients in cocktails is no easy task, but green Chartreuse is a bartender favorite that's required in acclaimed classics like the Last Word. “Chartreuse, in my opinion, is the king of liqueurs,” says Adam Gamboa, the lead bartender at Il Posto in Denver. “It's powerful, unique, smooth and versatile and leaves me questioning what hidden flavors and aromatics I have yet to discover.” He likes using it in gin-based cocktails, noting it complements a variety of ingredients, including lime, pineapple, absinthe and various herbs. But one unexpected friend of Chartreuse is whiskey, which has enough character to hold its own with the forceful liqueur. “Creating a beautifully balanced cocktail with Chartreuse can be challenging, as few spirits stand up to its bold profile,” he says, proving his point with his Chartreuse Manhattan. This drink is a variation on the classic Manhattan and the Tipperary cocktail. Green Chartreuse: What It Is and How to Use It.