Preheat oven to 300°.
Heat milk in a heavy saucepan over medium heat to 180° or until tiny bubbles form around edge (do not boil), stirring occasionally. Remove from heat; add chocolate, stirring occasionally, until chocolate melts. Stir in extracts.
Combine egg yolk and salt in a small bowl; stir well with a whisk. Gradually add milk mixture to egg mixture, stirring constantly with a whisk. Divide mixture evenly among 6 (4-ounce) ramekins, custard cups, or shallow baking dishes. Place ramekins in a 13 x 9-inch baking pan, and add hot water to pan to a depth of 1 inch.
Bake at 300° for 40 minutes or until center barely moves when ramekin is touched. Remove ramekins from pan, and cool completely on a wire rack. Cover ramekins, and chill at least 4 hours or overnight.
Sift 1 teaspoon sugar evenly over each custard. Holding a kitchen torch about 2 inches from top of each custard, heat sugar, moving torch back and forth, until sugar is completely melted and caramelized. Top with 1 tablespoon whipped topping. Serve custards immediately.