Preheat the oven to 350F
Line an 8X8 square pan with parchment paper, making sure to leave overhang so you can lift the brownies out when they are done (if you only have one pan and it is being used for the frozen filling, feel free to now put that filling in a bag while you make the rest of the recipe)
Measure out the chocolate chips and place them in a heat-proof bowl or measuring cup, set aside. In a medium saucepan, add the butter and turn the heat to medium, turn the heat to medium-high, and let the butter foam and sputter until it starts to turn a golden brown. Swirl the pan around making sure to remove the pan from the heat as you see the butter darken to a deeper brown. Pour the browned butter directly over the chocolate chips and let sit for at least 3 minutes. The heat of the butter will melt the chips!
Then stir using a spoon or nonstick spatula until the chips and the butter are completely smooth. In a separate large bowl add the granulated sugar, light brown sugar, eggs, vanilla extract, and both cocoa powders.
Whisk vigorously until the mixture is completely smooth and lightens in color. Add in the browned butter and chocolate mixture and mix until smooth. Add in the flour and salt and mix again until smooth. Pour all of the batter in the pan and smooth it out with an offset spatula. Bake just the brownie base for 25 minutes, and remove from oven (it will be have a shiny top but still be gooey and raw underneath). Remove the frozen Oreo cream from the freezer and carefully place it on top of the undercooked brownie layer, it should rest right on top.
Working quickly, scoop the cookie dough on top of the Oreo filling and spread into an even layer
Bake until completely cooked through about 50 minutes (if cookies look like they are getting too brown on top, place foil over the top of the bars 1/2 way through cooking)
Remove from oven and let cool COMPLETELY
Slice and enjoy!