1Heat oven to 350°F. Make cookie mix as directed on package, using oil, water and egg. Spread dough in ungreased 13 x9-inch pan. Bake 10 minutes just until dough is set.
2Meanwhile, heat jar of marshmallow crème in microwave uncovered on Low 30 seconds; spread over partially baked crust. Sprinkle with chopped cookies and chocolate candies.
3Bake 12 to 14 minutes longer or until marshmallows just begin to brown. Cool completely, about 1 hour.