Yield: Six or 7 4-ounce ramekins
4 ounces unsweetened chocolate, chopped into small pieces
2 cups heavy cream
1 tsp grated orange zest-optional
4 large egg yolks
1/3 cup sugar
1 1/2 tsp vanilla extract
ramekins, a wire whisk, a sieve; a bowl and a large 4-cup measuring cup, or 2 mixing bowls, a baking pan large enough to serve as a water bath for all the ramekins.
Preheat the oven to 350. Put the chopped chocolate in the large measuring cup or one of the bowls and melt in the microwave and then set the sieve on top. Pour the cream into a medium saucepan and bring to the simmer, then remove from the heat. If using orange zest, stir it into the cream before heating and steep 5 minutes covered, off the heat.
Meanwhile, whisk the yolks in the empty bowl, adding the sugar gradually. Continue whisking for a minute or more, until the yolks are pale yellow and thick and form a ribbon when dropped from the whisk.
Pour the hot cream into the yolks, stirring--not beating-- with the whisk, until evenly blended. Immediately pour this custard through the sieve over the chocolate, removing any coagulated bits of eggs, and stir gently with a large spoon to melt the chocolate and blend it into the custard. Stir in the vanilla extract. Skim off surface bubbles.
Arrange the ramekins in the baking pan, fill each with 1/2 cup of custard. Set the baking in the oven and pour in hot water to come halfway up the ramekins.
Bake the custards for about 25 minutes, or until the tops are just set. The custard will still be quite soft. Carefully remove the baking pan from the oven and lift the ramekins from the hot water. Let them cool briefly, then chill in the refrigerator, at least 4 hours, before serving.
Forming the brown-sugar crust.
Loosen the brown sugar if packed and break up any lumps with your fingers. Sprinkle a tablespoon or so over each custard and smooth it gently with the back of a spoon, forming an even layer of sugar that completely covers the surface.. Set the ramekins on a heatproof
tray and turn the broiler on watching them like a hawk until it bubbles. If you see smoke---pull it out immediately! If the ramekins have been heated by the broiler, chill them briefly before serving.