Take your butter and put it in a light colored or stainless pot or pan on med-med high heat. Butter can be cold, but I find this process smoother if the butter is room temperature. Stir the butter as it melts, and once the fats start to turn a golden brown and smell nutty, remove from heat and pour butter into a bowl to cool off. Butter goes from browned to burnt quite quickly so don't leave your butter unattended!
Preheat oven to 350°F and line an 8x8 pan with parchment.
After about 5 minutes, add both kinds of sugar to the bowl with your butter and mix until combined. You can use a mixer but hand mixing works great.
Once combined, add in eggs and mix until thoroughly combined, then stir in vanilla extract.
Take 10 oreos (setting aside 5) and crush them. I don't use a food processor for this because I like slightly bigger chunks. I put them in a baggie and use something to crush them up.
In a separate bowl, mix together flour, salt and baking powder.
Add dry ingredients into wet and mix until flour is JUST combined.
Add the crushed oreos to the batter and fold in.
Pour batter into prepped pan, and top with the additional 5 oreos. I break this by hand so the top has some larger and some smaller pieces.
Bake for about 35 minutes on center rack of oven. A toothpick inserted should come out cleanly. Let cool in pan for at least 3 hours before cutting into them.
