Microwave butter in large microwaveable bowl on HIGH 30 sec. or until melted. Add dry gelatin mix and marshmallows; toss to coat. Microwave 1 min. or until marshmallows are completely melted and mixture is blended, stirring after 45 sec. Add cereal; mix well.
Press cereal mixture onto bottom and up side of 9-inch pie plate sprayed with cooking spray.
Beat pudding mix and milk with whisk 2 min.; pour into crust. Refrigerate 2 hours or until firm. Garnish with strawberries.