1Preheat oven (350 degrees).
Combine cake mix, egg & 2/3 cup butter. Pat into a lg. jellyroll pan (or cookie sheet with a lip). Bake 12 min. Remove from oven and add marshmallows on top. Bake 1 - 2 min. more until melted, (don't try to smooth them out as it doesn't work).
2Melt together peanut butter chips, the 1/4 cup butter, vanilla and corn syrup in lg. microwave bowl preferably. Add Rice Krispies and peanuts. Pour over the marshmallow/cake layer. Cool and cut into bars. Enjoy