The night before, fill an ice-cube tray with milk. Freeze solid. Chill brewed coffee in refrigerator. Finish in two batches, so the blender won't overflow: place half the milk cubes in the container. Add half the coffee and one teaspoon of the sugar and blend until smooth. Add one ounce chopped chocolate and blend 10-30 seconds, until chocolate is well blended. Pour into tall frosted glasses and repeat with the remaining ingredients. Serves 2.
