In a small saucepan, combine all ingredients except unsweetened cocoa powder.
Cook over low heat until chocolate is melted and mixture is smooth, stirring constantly.
Place pan in a bowl of ice water to speed chilling, stirring mixture occasionally.
Sift a light layer of cocoa powder on a cookie sheet.
When chocolate mixture is cooled and slightly thickened, spoon into a decorating bag fitted with desired decorative tip, or truffles may dropped by teaspoonfuls onto cocoa dusted sheet pan and then rolled by hand.
Sift remaining cocoa powder over truffles. Store tightly covered in refrigerator, let stand at room temperature for 30 minutes before serving.