1. Combine cherries, pistachios, and ginger in a medium bowl, stirring well. Line baking sheet with heavy-duty foil; chill pan.
2. Place chocolate in a double boiler or a heatproof bowl; cook over simmering water until chocolate is melted, stirring frequently (about 5 minutes). Stir in half of fruit mixture; spread onto prepared pan. Using a rubber spatula, spread chocolate mixture evenly into an 11- x 9-inch rectangle. Immediately sprinkle the remaining fruit mixture evenly over top of the chocolate mixture; chill (about 10 minutes).
3. Break into 10 (3-inch) pieces; serve.