2 cups whipping cream
1/2 cup whole milk
5 ounces bittersweet (not unsweetened) or semisweet chocolate, chopped
6 large egg yolks
1/3 cup sugar
Preheat oven to 325°F. Bring cream and milk just to simmer in heavy medium saucepan over medium heat. Remove from heat. Add chocolate; whisk until melted and smooth. Whisk yolks and sugar in large bowl to blend. Gradually whisk in hot chocolate mixture. Strain mixture into another bowl. Cool 10 minutes, skimming any foam from surface.
Divide custard mixture among six 3/4-cup custard cups or soufflé dishes. Cover each with foil. Place cups in large baking pan. Add enough hot water to pan to come halfway up sides of cups. Bake until custards are set but centers still move slightly when gently shaken, about 55 minutes. Remove from water. Remove foil. Chill custards until cold, about 3 hours. (Can be made 2 days ahead. Cover and keep chilled.)