PLACE marshmallow creme, butter, vanilla and salt in large bowl; beat with electric mixer on medium speed until well blended. Gradually add sugar, beating until well blended.
SHAPE into balls with hands lightly dusted with additional powdered sugar. (If necessary, refrigerate marshmallow creme mixture 30 minutes or until firm enough to handle.) Place balls on wax paper-covered baking sheet or tray. Refrigerate until firm.
MELT chocolate in microwavable bowl as directed on package. Cool slightly. Add balls, 1 at a time, to chocolate; stir gently to evenly coat with chocolate. Remove balls from chocolate with fork; scrape off excess chocolate on rim of bowl. Return to baking sheet; refrigerate until set.