Melt butter in a medium skillet over medium heat, swirling the pan occasionally. (Turn off the heat here if you're skipping the browning!) After melting, it will start to simmer and look foamy. Swirl some more. The foam will start to clear, and the solids at the bottom will begin to brown. It should take 10-12 minutes to start seeing some nice brown bits. Immediately pour into the bowl of your stand mixer, or a large bowl if you're using a hand mixer, and allow to cool.

Heat oven to 350°. Prepare a 13x9" baking pan by lining with parchment paper, leaving a few inches to hang over each side to use as a sling for removing the blondies when they're done baking. Give the paper a good spritz with nonstick spray.

In a small mixing bowl whisk together the flour, salt, and baking powder. Set aside. In stand mixer with the paddle attachment, or a bowl with a hand mixer, beat together the butter and brown sugar for 1-2 minutes until lighter in color and fluffy. Add eggs and vanilla and beat another 2 minutes, scraping down the sides if necessary. Gradually add in the flour mixture and beat on low speed until just combined and no flour pockets remain. Stir in the chopped Oreo cookies and cookies n' cream chocolate with a large spatula, saving some of the goodies to put on the top of the bars before baking (because it’s pretty ☺️). Spread batter evenly into prepared pan and top with remaining chocolate and cookies.

Bake blondies until the edges are just golden, about 22 minutes or until a toothpick inserted into the center comes out mostly or completely clean. Cool completely on a wire rack, and then cut into squares. Enjoy!