Preheat oven to 350 degrees. Prepare an 9×9 pan with foil, leaving sides overhanging for easy removal later.
Make the chocolate chip cookie dough. Sift together the flour, salt, baking powder and baking soda. In a separate bowl, cream together the butter and sugars. Add the egg and vanilla. Add the dry ingredients to the wet and mix until combined. Add the chocolate chips.
Make the brownie batter. Sift together the dry ingredients in a medium sized bowl. In a separate bowl, cream together the butter, the peanut butter and the sugars. Add egg and vanilla. Add the dry ingredients to the wet and mix until combined. Set aside.
Scoop the chocolate chip cookie dough into the bottom of the pan–pressing down to ensure an even coverage. You may have a little bit left over if you want to sample it.
Open the Oreos. Eat one. Eat another one. Stop eating them. Make a nice layer of Oreos on top of the cookie dough. You don’t need to get them super close together. You don’t need to overlap them. Just a layer….don’t stress so much about the details.
Pour the brownie mixture on top of the Oreo layer. My brownie was a bit thick so I poured it on in glops and used a spatula to smooth it out. It worked wonderfully. You just want a nice even brownie layer over the top of the Oreo layer over the top of the chocolate chip cookie dough layer.
Bake for 35-40 minutes. Check with a toothpick to ensure it is cooked all the way through.
Let cool for 20 minutes before removing the foil from the pan. Cut into little squares and watch them be devoured quickly.