Preheat oven to 300°. Combine 1/2 cup cream and chocolate in a heavy saucepan; cook over low heat, stirring constantly, 2 to 3 minutes or until chocolate is melted. Remove from heat. Stir in vanilla and remaining 1 1/2 cups cream.
Whisk together egg yolks and 1/4 cup sugar until sugar is dissolved and mixture is thick and pale yellow. Add cream mixture, whisking until well blended. Pour mixture through a fine wire-mesh strainer into a large bowl.
Spoon 1 1/2 Tbsp. cranberry sauce into each of 6 (4-oz.) ramekins. Pour cream mixture into ramekins; place ramekins in a large roasting pan. Add water to pan to depth of 1/2 inch.
Bake at 300° for 45 to 55 minutes or until edges are set. Cool custards in pan on a wire rack 25 minutes. Remove ramekins from water; cover and chill 8 hours.
Preheat broiler with oven rack 5 inches from heat. Sprinkle remaining sugar over ramekins. Fill a large roasting pan or 15- x 10-inch jelly-roll pan with ice; arrange ramekins in pan.
Broil 3 to 5 minutes or until sugar is melted and caramelized. Let stand 5 minutes. Garnish, if desired.
Test Kitchen Tip: Filling the roasting pan with ice before broiling keeps the custards cool while caramelizing the tops.
All That Glitters. Tissue-thin flakes of edible gold leaf add instant glamour to a flurry of holiday garnishes--from fresh cranberries to shards of coarsely chopped white chocolate. It's super easy to apply--just press it on. Order online from surlatable.com, fancyflours.com, or goldleafcompany.com ($28-$41). It's a splurge, but when stored in a dry place it will last for years of celebrations to come.