In a microwave safe bowl melt the butter and transfer into a mixing bowl. Add the brown sugar and whisk to combine. Add the vanilla and egg and continue to whisk until totally incorporated.
In another bowl mix together the dry ingredients, flour, baking powder, salt, and baking soda.
Slowly add the dry ingredients to the wet ingredients until fully combined. Stir in the white chocolate and set the batter aside
For the Cookie Dough layer:
Cream together the butter and sugars in a mixer. Add the egg and vanilla, making sure to scrape down the sides of the mixing bowl. Add the flour, salt, baking soda and baking powder and mix on low until everything is incorporated. Set aside.
Assembly:
Pre-heat the oven to 350 degrees.
Line the bottom of a 9x9 baking pan with tin foil and then spray the tin foil with a layer of baking spray.
Layer the cookie dough on the bottom of a 9x9 baking pan, pressing down to form the bottom of the slutty brownies.
Layer as many oreos that will fit on top of the cookie dough. No need to overlap. One single layer will do.
Since the blondie brownie batter is thick, carefully press the brownie batter on top of the oreo layer and make sure it's even on top.
Bake for 30-35 minutes. Test with a knife to see if the center is done. If the knife comes out clean, let the brownies rest for at least 1 hour before serving. If the knife comes out with batter still on it, allow the brownies to bake about 5 minutes more.
Serve with ice cream if desired :)
Notes
It's super important to let these brownies rest for at least an hour before serving. I like to put the whole pan in the fridge to let them tighten up a bit and then cut and serve!