They are wonderful!
Here you go.....
http://www.flavorsbyfour.blogspot.ca/2011/12/buckeye-brownies-and-our-one-year-blog.html
It was my first try. The peanut butter layer needed more milk than they suggested, but it might have been because the butter was still too cold.
Oh my goodness, they look scrumptious! I have a chocolate cake mix. I wonder how a sheet cake would be with those two toppings.... Thank you for posting!