On a parchment-lined baking pan, spread brown sugar in an even layer. Set aside in a cool, dry place until sugar dries out a bit, about 2 hours.
Meanwhile, in a medium pot over medium-high heat, bring cream, coffee beans, and vanilla-bean pod and seeds to a boil. Immediately remove pot from heat and let mixture steep to room temperature, about 1 hour. Strain and discard solids.
Preheat oven to 325 degrees F. Meanwhile, in a large pot over high heat, boil 1 1/2 quarts water. Meanwhile, in a large bowl, whisk yolks with granulated sugar until thick and pale yellow. Using a whisk, stir in cooled cream (do not create bubbles or froth) until fully mixed. Set six 8-ounce ramekins in a large roasting pan and evenly divide custard mixture among the ramekins. Allow liquid to settle, then skim any foam from the top. Transfer pan to oven and carefully pour hot water into pan until water reaches halfway up sides of ramekins. Bake until custards are set at outer edges and the centers jiggle slightly, about 35 minutes. Immediately transfer ramekins to a wire rack and let cool to room temperature. Cover ramekins with plastic wrap and refrigerate for about 2 hours.
Meanwhile, press reserved brown sugar through a sieve and into a small bowl. Preheat broiler, with a rack in the top position. (Ramekins should sit about 3 inches beneath the flame or heating element. If necessary, use an upside-down baking pan as a riser.) Remove ramekins from refrigerator and place on a baking sheet. Using a paper towel, blot any moisture that has accumulated on the custard tops, then sprinkle a scant tablespoon of brown sugar on each. Place baking sheet under broiler until sugar is bubbling and deep brown, 2 1/2 to 3 minutes. Immediately transfer ramekins to a wire rack for 1 minute to let topping harden. Serve immediately.