Preheat the oven to 300 degrees F.
Put the chocolate in large bowl and set aside. Bring the cream and milk, just to a boil, in a large saucepan over medium-low heat. Pour the mixture over the chocolate and cover with plastic wrap. Let sit for 10 minutes. Meanwhile, whisk the espresso powder or extract, the egg yolks and sugar in a medium bowl until well combined. Remove the plastic wrap, and stir the chocolate and milk mixture with a spatula until well combined. The mixture should not be grainy.
Whisk the egg mixture slowly into the chocolate until incorporated. Arrange 12 ramekins in a large, deep baking dish filled halfway with water. Pour the chocolate mixture evenly into the ramekins. Put the baking dish in the oven and bake for 30 minutes. Remove from the oven, carefully take the ramekins from the water bath and let cool. Put a teaspoon of creme fraiche on each portion and serve immediately.
This recipe was provided by a chef, restaurant or culinary professional. It has not been tested for home use.