Method

1. Position the rack in the centre of the oven and preheat the oven to 250°F.
2. Whisk the cream, milk, sugar, and vanilla in a medium heavy saucepan to blend and bring to a boil over medium heat.
3. Add the chocolate and whisk until all the chocolate has melted.
4. Remove from the heat.
5. Using a whisk, stir the egg yolks in a large bowl to blend.
6. Then, in a slow, steady stream, add the chocolate-cream mixture, whisking until smooth.
7. Divide the mixture among 6 ramekins or small custard cups (each about 5 ½ ounces), and place them in a large high-sided baking dish or baking pan.
8. Carefully transfer the pan to the centre rack in the oven.
9. Add enough cold water to the baking dish so that it comes halfway up the sides of the ramekins or custard bowls.
10. Bake for about 1 hour, or until the custards jiggle slightly in the centre when gently shaken (the custards will thicken as they chill).
11. Let cool to room temperature and then refrigerate until cold.
12. Serve cool.