I found this recipe on the side of the Pillsbury cake mix and decided to try it. While tasty, they are not as good as the Decadent Peanut Butter Brownies and instead of using jar frosting as suggested by the recipe, I made the frosting similar to what I use on the Cookie Pizza.
Yellow cake mix
1 cup chunky peanut butter
1/3 cup water
Spray 9×13 pan with cooking spray. Fill pan with mix and bake at 350 for 20 to 25 minutes. Cool completely before frosting.
For the frosting, mix:
1/2 cup peanut
8 oz chocolate chips, melted
Chop up nuts or candy bars to decorate the top.
Side note, the pan I use for brownies has a locking lid with handle that makes it great for traveling. I got it around 4th of July about 5 summers ago for $4 and I wish I would have bought the other one sitting on the clearance shelf because I love this pan-lid combo!