Super easy to make. Good luck being able to stop eating these bars. The peanut butter and marshmallow flavors along with the different textures are addicting.
Heat oven to 350°F. Spray bottom of 13×9-inch pan with cooking spray or line pan with non-stick foil so they are easy to pull out and cut.
In large bowl, stir cookie mix, oil, water and egg until soft dough forms. Press dough in pan using floured fingers.
Bake 12 to 15 minutes or until set. Immediately sprinkle marshmallows over crust; bake 1 to 2 minutes longer or until marshmallows begin to puff.
In a small saucepan, cook corn syrup, butter, vanilla and chips over low heat, stirring constantly, until chips are melted. Remove from heat; stir in cereal and peanuts.
Immediately spoon cereal mixture evenly over marshmallows. Cool at room temperature until firm enough to cut, approximately 4 hours.