In a large bowl, stir together cookie mix and crumbs. Stir in melted butter until softball of dough forms. Press into ungreased 13x9-inch pan.
Bake 18 to 20 minutes or until set on 375 degrees. Immediately sprinkle chocolate chips over crust. Let stand 3 to 5 minutes or until chocolate begins to melt. Spread chocolate evenly over crust.
Sprinkle marshmallows over melted chocolate. Broil with top 5 to 6 inches from heat 20 to 30 seconds or until marshmallows are toasted. (Watch closely; marshmallows will brown quickly.)
Cool before cutting for 10-15 minutes. Serve warm. Store any remaining bars tightly covered.