Heat oven to 350°.

In large bowl combine the cake mix, butter and egg at low speed until the entire mixture is crumbly and moist.

Press the mixture into the bottom of an ungreased 9x13 pan. Bake for 16 minutes at 350°.

Remove the pan from the oven and sprinkle with marshmallows. Immediately return the pan to the oven and bake for an additional 3 minutes, or until the marshmallows just begin to puff.

Meanwhile, add the corn syrup, butter, peanut butter and peanut butter chips to a large saucepan and place over medium heat. Cook, stirring constantly, just until chips are melted and the mixture is smooth. Add the vanilla and salt to the mixture and stir.

Remove the saucepan from the heat and quickly stir in the cereal and nuts. Immediately spoon the warm topping over the marshmallow layer, spreading to cover. Chill the bars until they reach room temperature.

Cut and serve.