MICROWAVE butter and 1 oz. chocolate in large microwaveable bowl on HIGH 45 sec. or until butter is melted; stir until chocolate is completely melted and mixture is well blended. Add marshmallows; toss to coat. Microwave 1-1/2 min. or until marshmallows are completely melted and mixture is well blended, stirring after 45 sec.
ADD cereal; mix well. Press onto bottom of 13x9-inch pan sprayed with cooking spray. Cool. Cut into 54 bars.
MIX MALLOW Bits and candies. Melt remaining chocolate as directed on package. Dip each bar halfway into chocolate; let excess chocolate drip off. Dip in MALLOW Bits mixture; place on waxed paper-covered baking sheet. Refrigerate until chocolate is firm.