How to Make It
Preheat oven to 300°.
Bring milk, 2 tablespoons granulated sugar, and salt to a simmer in a medium, heavy saucepan (do not boil). Remove pan from heat; add chocolate, stirring until chocolate melts. Combine remaining 2 tablespoons granulated sugar, eggs, and egg yolks in a medium bowl, stirring well with a whisk. Gradually add milk mixture to egg mixture, stirring constantly with a whisk. Stir in liqueur and vanilla. Divide mixture evenly among 6 (4-ounce) ramekins. Place ramekins in a 13 x 9-inch baking pan; add hot water to pan to a depth of 1 inch. Bake at 300° for 50 minutes or until center barely moves when ramekin is touched. Remove ramekins from pan; cool completely on a wire rack. Cover and chill at least 4 hours or overnight.
Sift 2 tablespoons superfine sugar evenly over custards. Holding a kitchen blowtorch about 2 inches from top of each custard, heat sugar, moving torch back and forth until sugar is completely melted and caramelized (about 1 minute). Serve immediately.