Preheat oven to 350 degrees F. Lightly grease a 13 by 9-inch baking pan.

In a large bowl or bowl of a stand mixer, combine the flour, sugar, baking soda, baking powder, salt, melted butter and egg. Stir until well blended and then mix in the milk. (This can also be done by hand). Pat the mixture into a prepared pan and set aside.

In a stand mixer, or with a hand mixer, beat the cream cheese until smooth. Add the remaining 2 eggs, and the cocoa powder. Lower the speed of the mixer, and add the powdered sugar. Continue beating until ingredients are well mixed. Slowly add the remaining 1 stick of melted butter, and the vanilla, continuing to beat the mixture until smooth. Spread the filling over the cake mixture in the pan. Press 18 whole Oreos into the filling (the filling will begin to spill over the oreos, but it probably will not completely cover the oreos). Bake for 40 to 50 minutes. Be careful not to overcook the cake. The center should still be a little giggly when finished baking. Let sit five minutes.

While the cake is sitting chop the remaining Oreos into pieces and melt the chocolate chips and peanut butter together (I use the microwave, stirring every 30 seconds until melted).

Once you melted the peanut butter and chocolate, evenly the distribute the chopped Oreos all over the top of the cake. Pour the melted chocolate mixture over top, spreading with a spatula. Make sure chocolate gets down into the Oreo crevices, as it is the “glue” that holds the top to the bottom (do the best you can, but the chocolate will probably not reach all the way to the very edge of the cake). Refrigerate for 2 hours before serving.

Let bars sit at room temperature for 15 minutes before cutting. Try and cut them carfully, but beware that the tops might crack a little.