These brownies are awesome. Each time I've taken them somewhere people have raved. They started out as a cookie, but they were kind of a pain to make, so I tried them in brownie form, and they were a hit.
You can tell how busy I am by how many recipes I'm making with a mix instead of from scratch. There have been a lot lately! This is based on a mix, but you can use a homemade brownie recipe. I also used the kind of brownie mix that comes with frosting. If you want to make your own, I like my chocolate sheet cake frosting.
1 box of 9 x 13 brownie mix with frosting included (plus whatever it calls for: eggs, oil, etc)
1 c. powdered sugar
1 c. peanut butter
Prepare the brownie mix according to the box. Pour into a greased and floured 9 x 13 pan. Mix the powdered sugar and the peanut butter. Smoosh it out a little with your hands to flatten it, and then drop evenly on the top of the brownie dough. Bake at 350 for 30 minutes. Let cool for 5 minutes or so, then pour the chocolate frosting on the brownies. Let cool and then cut.