Adding just a hint of fire & brimstone in the form of 1 tsp mezcal is a nice riff on Kilgore's Purgatory. Thematically, it seems most appropriate to use the smoky Del Maguey Vida de Muertos.

Made it with Milagro Reposado; no Punt e Mes so used Alessio Rosso, which was great in this drink and works well with Difford's chocolate garnish suggestion. Squares of chocolate do not skewer well on toothpicks or cocktail swords and a square of chocolate at the bottom of a cocktail glass looks more like a mistake than a garnish so I did something I've done before (e.g., "Munich Negroni Western Style") and grated a light dusting of chocolate over the drink, which enhances the nose as well.

R. Elgar proposed more traditional Manhattan proportions for this, with 3/4 oz rosso vermouth and 1/4 oz Benedictine for 2 oz rye, which works well particularly if you offset the added sweetness of Benedictine by using a vermouth amaro if you want an aperitif cocktail rather than a dessert drink. I've now tried this with Punt e Mes, Dopo Teatro, and Tempus Fugit "Alessio" (which I also regard as a vermouth amaro), and all work well for that purpose. Elgar's early comment referred to "an absinthe...made in New Orleans," which had to be Herbsaint, and Marie T. Straus recommended Herbsaint, too, so I tried rinsing an Old Fashioned, per C. Lopez, with Herbsaint instead of absinthe; a very N'awlins touch.

Don't know how you miss Mardi Gras as an occasion on the Difford's Guide calendar! Good excuse to revisit and tweak the Grand Sazerac.