Microwave bittersweet chocolate, cream and butter in microwaveable bowl on HIGH 1-1/2 to 2 min., stirring after 1 min. Stir until chocolate is completely melted; cover. Freeze 1 hour or until firm enough to handle. Use teaspoon to scoop and roll chocolate mixture into 20 balls, each about 1 inch in diameter; place on waxed paper-covered baking sheet. Freeze 20 min.