BEAT pudding mix and milk in medium bowl with whisk 2 min. (Pudding will be thick.) Stir in COOL WHIP.
SPOON onto 16 graham squares. Top each with second graham square to make sandwich; press together gently to secure. Place in shallow pan; cover.
FREEZE 2 hours or until firm. Transfer to airtight container. Store in freezer up to 2 weeks.