How to Make It
Preheat the oven to 325°. Set an 8-inch round soufflé dish in a small roasting pan. In a medium saucepan, whisk the cream with the espresso powder and bring just to a simmer over moderately high heat. Remove from the heat, add the chocolate and let stand for 2 minutes; whisk until smooth.
In a large bowl, whisk the eggs and yolks with the sugar and salt. Gradually whisk in one-fourth of the hot chocolate cream until smooth; gradually whisk in the remaining cream. Strain the pudding through a fine sieve into the soufflé dish. Add enough hot water to the roasting pan to reach halfway up the side of the soufflé dish. Bake the pudding for about 50 minutes, until just set. Let cool slightly and then remove from the water bath and let cool completely.
Spread the brioche on a baking sheet and toast in the oven until golden, about 12 minutes. Transfer the croutons to a bowl and let cool completely. Wipe off the baking sheet and line it with a sheet of parchment paper.
In a medium saucepan, combine the sugar with 1/4 cup of water and cook over moderately high heat, stirring occasionally, until the temperature reaches 240° on a candy thermometer, about 7 minutes. Stir in the brioche and cook, stirring, until the croutons are coated in an amber caramel, 3 to 5 minutes. Spread on the prepared baking sheet and sprinkle with cinnamon. Let cool completely, then coarsely crush the candied croutons.
In a blender, combine the 1/4 cup of warm heavy cream with the sugar and one-fourth of the candied croutons; puree until smooth. Let cool.
In a large bowl, using a hand mixer, beat the 1/2 cup of cold heavy cream at high speed until soft peaks form. Fold in the candied brioche cream and beat at high speed until stiff peaks form. Spoon the chocolate pot de crème into glasses and top with the candied brioche whipped cream and the remaining candied croutons.