Preparation

• Line 13x9-inch pan with foil, with ends of foil extending over sides; spray with cooking spray.
• Combine RITZ Bits and cookies.
• Microwave butter in large microwaveable bowl on HIGH 45 sec. or until melted. Add marshmallows; stir to evenly coat marshmallows with butter.  Microwave 1 min. or until marshmallows are completely melted and mixture is well blended, stirring every 30 sec.
• Reserve 1/2 cup RITZ Bits mixture for later use.  Add remaining RITZ Bits mixture to melted marshmallow mixture along with the popcorn; mix well. 
• Press popcorn mixture onto bottom of prepared pan. Sprinkle with reserved RITZ Bits mixture; press gently into popcorn mixture to secure. Cool completely.
• Use foil handles to remove popcorn mixture from pan before cutting into bars.