Preheat the oven to 325 degrees F. Arrange 6 (6-ounce) ramekins in a roasting pan.
Place the chopped chocolate in a bowl. In a heavy medium saucepan, combine the heavy cream and instant espresso powder and bring almost to a simmer over medium heat. Pour the hot cream over the chocolate. Allow to sit 1 minute. Using a whisk, combine the ingredients until the chocolate melts completely and the mixture is smooth. (You could also heat the cream in the microwave until almost boiling. Pour over the chocolate and espresso powder. Let sit 2 minutes, and then whisk to combine.)
Whisk the egg yolks, orange zest and sugar in large bowl to blend. Gradually whisk in the hot chocolate mixture and stir until the ingredients are incorporated.
Divide the custard equally among the cups using either a 4-ounce ladle or a 6-ounce ladle. Using a wet paper towel, clean up the sides of the ramekins, if needed. Pour enough hot water into the pan to come halfway up the sides of the cups. (You could also place the ramekins in the roasting pan, place the pan in the oven and pour the water into the pan, halfway up the sides of the ramekins.) Bake the custards until just set around the edges but still soft in the center, 35 to 40 minutes. Carefully remove the ramekins from the water. Refrigerate, uncovered, until cold.
Sprinkle 1 to 2 teaspoons sugar evenly over each custard. Pick up the ramekin and gently swirl the sugar to evenly distribute. Working with 1 pot de creme at a time, hold a blowtorch so that the flame is 2 inches above the surface. Starting in the center and working in a circular motion, heat the sugar until it melts and caramelizes.
Cook's Note: Feel free to try different chocolates or a combination of 2 or more. Milk chocolate adds mellow sweetness to the mix, while bittersweet chocolate adds a rich complexity. I find kids (and the kid in some adults) clamor for the milk chocolate and many adults adore the semisweet or bittersweet. Alternately, play with flavors. Swap out the espresso powder for a splash of raspberry liqueur, like Chambord or Framboise for a fruity finish. Experiment and find what you love-it's fun!
Propane gas torches are highly flammable and should be kept away from heat, open flame, and prolonged exposure to sunlight. They should only be used in well-ventilated areas. When lighting a propane gas torch, place the torch on a flat, steady surface, facing away from you. Light the match or lighter and then open the gas valve. Light the gas jet, and blow out the match. Always turn off the burner valve to "finger tight" when finished using the torch. Children should never use a propane gas torch without adult supervision.