Chocolate Creme Brûlée

Preheat the oven to 300 degrees (F). Place six (8-ounce) ramekins in a large flat-bottomed roasting pan. The pan should be large enough to hold all of the ramekins with a little space between each one and the ramekins should be completely flat. If you don’t have a pan this size, simply use multiple pans. Set aside until needed. 
In a large heatproof bowl, whisk together the egg yolks and sugar until just combined. Set aside. (Note: this is a good time to bring a tea kettle or pot of water to a rolling boil. You’ll need freshly boiled water to pour into the baking sheet for the water bath later in this recipe.)
Pour the heavy cream into a heavy-bottomed saucepan. Place the pan over medium heat and cook just until small bubbles start to firm around the edges and center of the pan. Do not bring to a full boil. 
Remove the pan from heat. Immediately add in the chocolate and espresso powder and vigorously whisk until the chocolate is completely melted. 
In a slow and steady stream, whisk the cream mixture into the egg mixture, mixing until evenly combined. Whisk in the Kahlua and vanilla extract. 
Transfer the mixture into a large spouted measuring cup or bowl. Pour the mixture into the prepared ramekins, filling each one all the way up to the top.  

Place the pan on the center rack in the oven and slowly (and carefully!) pour freshly boiled water into the pan until it’s halfway up the sides of the ramekins. Take care not to get any water on the custards! 
Bake for 38 to 40 minutes, or until the custards are set at the edges, but still a little jiggly in the middle when gently shaken. 
Remove the custards from the water bath, cool to room temperature, then loosely cover and refrigerate for at least 6 hours, or up to 48 hours. 
20 minutes before you plan on serving, remove from the fridge and allow custards to come to room temperature. Do not try to brûlée while still cold. 
To serve: Sprinkle 1 tablespoon of fine caster sugar evenly on top of each custard. Hold a kitchen blowtorch one inch from the surface of the custard and blaze the sugar until it caramelizes evenly. Repeat with all custards.
Optional: Top with a small swirl of whipped cream, fresh raspberries, and sprig of mint. Serve at once!