Preheat oven to 350 degrees F.
In a microwave safe bowl, heat the butter and chocolate chips in 30 second intervals, until chocolate is melted, stirring to incorporate butter and chocolate. Set aside.
In a large bowl, using a hand mixer, beat the eggs, granulated sugar, brown, sugar, vanilla extract, salt, and baking powder for 5 minutes, until egg mixture is thick and creamy.
Gradually mix the chocolate mixture to the wet ingredients, beating well, until fully incorporated.
Add the flour to the brownie batter and mix until well incorporated. Stir the oreo pieces into the brownie batter.
Using a large cookie scoop, place brownies on prepared baking sheet leaving at least 2 inches between scoops of dough. Top with extra oreo cookie pieces if desired.
Bake for 10 minutes, remove cookies from the oven and allow to cool for 1-2 minutes before removing from the baking sheet.
Cool completely on a wire rack.