In a medium saucepan, combine 2 1/2 cups of cream, espresso beans and sugar. If using the vanilla bean, cut in half lengthwise; scrape out vanilla seeds. Add scraped pod and seeds to cream mixture. (If using vanilla extract, it will be added later.).
Heat mixture until small bubbles form around edge of pan. Remove from heat; cover and let steep 30-40 min or until cream has taken on a good coffee flavor.
Heat the oven to 400ºF.
Place 8 (1/2-3/4 c.) ramekins in shallow roasting pan.
Place chocolate and remaining 1/2 cup cream in metal bowl set over a pan of simmering water. Heat until melted, stirring occasionally.
In a large bowl, beat egg yolks until well blended. Strain espresso-cream mixture slowly into egg yolks, whisking constantly to combine. If using vanilla extract, stir into custard now.
Gradually whisk cream mixture into melted chocolate and then strain through a fine strainer.
Pour custard into ramekins. Create a water bath - add enough boiling water to roasting pan to reach halfway up the sides of the ramekins. Cover pan securely with foil.
Bake 50-60 min or until custards are set but still quivery like gelatin.
Remove ramekins with tongs from the hot water; cool on wire rack 30-40 minute or until room temperature. Cover with plastic wrap; refrigerate at least 1 hour or up to 24 hours.
Place oven rack 8 inches from broiler. Push the brown sugar through strainer over each custard, allowing about 2 teaspoons per custard.
Using fingers, gently spread brown sugar to distribute evenly. Place ramekins in the shallow roasting pan again and surround with ice cubes.
Broil 3-6 min or until brown sugar melts and caramelizes, watching carefully to prevent burning.
Cool to room temperature. Store in refrigerator - if made more than 4 hours ahead, topping will begin to soften and will no longer be crisp -- so do this last.