In a mixing bowl, beat the cake mix, peanut butter, and brown sugar at low speed until crumbly. Set aside ½ cup. Add water, eggs, and oil to the remaining crumb mixture: blend on low until moistened. Beat on high for 2 minutes. Stir in ¼ cup each of chocolate and peanut butter chips.
Pour into a greased 13”x8”x2” baking pan.
Combine peanuts, reserved crumb mixture, and remaining chips and sprinkle over batter.
Bake for 40–45 minutes or until a toothpick inserted near the center comes out clean.