12 ounces bittersweet chocolate, cut into 1/4-inch pieces
1/2 cup very strong, prepared, espresso coffee
8 pot de creme cups (4 to 5 ounces each)
Bring the cream and sugar to a boil with the vanilla bean in a saucepan.
Whisk yolks in a bowl. Whisk about a third of the boiling cream into the yolks. Return remaining cream to a boil and whisk in yolk mixture. Continue to cook, whisking constantly, another 15 or 20 seconds, until slightly thickened.
Strain cream into a bowl and add chocolate. Whisk smooth, whisk in coffee, and pour into molds. Refrigerate until cooled.
Serve the pots de creme alone, or with a crisp cookie. Storage suggestion: For advance preparation, cover the pots de creme with plastic wrap and refrigerate. Uncover and leave at room temperature for an hour before serving