In large bowl, stir cookie mix, oil, water and egg until soft dough forms. Press in pan using floured fingers. Bake 12-15 minutes or until set. Immediately sprinkle marshmallows over crust. Bake 1-2 minutes longer or until marshmallows begin to puff.
In 4 qt saucepan, cook corn syrup, butter, vanilla and chips over low heat, stirring constantly until chips are melted. Remove from heat and stir in cereal and nuts. Immediately spoon mixture evenly over marshmallows. Refrigerate 30 minutes or until firm.
