Don't believe what they've told you: You can indeed improve on a classic, especially when the cold-weather triple combines the cozy spice of buttered rum with the silky-smooth richness of hot chocolate, creating a drink that's luxurious and complex. It's an after-dinner drink and a luxurious dessert in one steaming hot mug.
Heat 2 oz. bittersweet chocolate, chopped, with ½ cup unsalted butter, cut into pieces, in a heatproof bowl set over a saucepan of barely simmering water (do not let bowl touch water), stirring, until smooth.
Remove from heat and whisk in ½ cup brown sugar, 1 tsp. ground cinnamon, and a pinch of kosher salt.
Bring 2 ½ cups water to a boil in a small saucepan. Remove from heat and whisk in chocolate mixture and ¾ cup dark rum.
Divide hot chocolate among mugs and top with whipped cream and freshly grated nutmeg. Makes 4 small servings.
