Mix Chambord liqueur, espresso and 1 T sugar. Put mixture in a pan and cook over medium heat, stirring constantly with a wooden spoon without stopping until mixture is reduced by half; allow to cool.
In a medium pan, scald cream and milk, and remove pan from heat. In a double boiler, melt chocolate; add to milk and cream mixture; allow to cool.
Place oven rack in the middle position; preheat oven to 300°F.
Working in a bowl, whisk yolks with remaining 2 T sugar until mixture is pale and thick. Very gradually and gently, whisk liquid into egg mixture , being careful not to create air bubbles.
Arrange 8 coffee cups or ramekins in a small roasting pan filled with warm water, leaving space between them and fill each cup or ramekin to the top with custard mixture. Cover pan tightly with foil. Put pan into oven and bake custards for about 40 minutes.
Remove pan from oven, allow to sit in water bath for 10 more minutes.
Pot de Creme can be prepared one day ahead and stored in the refrigerator. Serve at room temperature.