Put the chopped chocolate into a medium bowl.

Pour cream into a small heavy saucepan; stir in sugar. Place over medium heat and bring to a boil. Pour the hot cream over chocolate; stir until smooth and the chocolate is melted. Cover and refrigerate for 4 hours, or until thoroughly chilled.

For best results, put the mixing bowl and beaters in the refrigerator a few hours before you plan to beat the cream.

Transfer to a large bowl. Beat to spreading or piping consistency.  Refrigerate for about 1 hour before using.

Keep the whipped cream in refrigerator for up to 2 days.