In a small saucepan combine coffee, chocolate pieces, and sugar. Cook and stir over medium heat for 2 to 3 minutes or until chocolate is melted and sugar is dissolved.
In another small saucepan heat half-and-half or light cream until steaming, stirring occasionally. Pour coffee mixture into a mug. Add warm half-and-half. If desired, stir in additional sugar to taste. Makes 1 (12-ounce) serving.