Put cream, milk, sugar, vanilla bean, chocolate and espresso powder in a saucepan. Scald milk mixture. In a stainless steel bowl stir the egg yolks. Continue to stir egg yolks as you slowly pour the hot cream mixture over the yolks. Strain custard into a heat proof container with a pouring spout. Place four 3/4-cup ramekins in a shallow baking pan. Evenly pour the custard into the ramekins. Place the pan in the oven then pour boiling water into the baking pan so the water comes halfway up the sides of the ramekins. Cook about 30 to 35 minutes until only the custard centres jiggle slightly when the pan is moved. Remove the pan from the oven. Remove the ramekins from the pan and cool on a wire rack. Once the custards reach room temperature chill them in the refrigerator for at least 3 hours or overnight.
Sprinkle each custard top with a teaspoon of brown sugar. Caramelize the sugar with a crème brûlée torch or under the broiler.