Slutty Brownies

10 tablespoons unsalted butter 3/4 cup cocoa powder 1 1/4 cups white sugar 1/2 teaspoon salt 2 teaspoons vanilla extract 2 large eggs 1/2 cup all-purpose flour 1 package Oreos (regular or double stuffed) 1 cup unsalted butter (at room temperature) 1/2 cup brown sugar 1 1/2 cups white sugar 2 eggs 2 1/2 cups all-purpose flour 2 1/2 teaspoons vanilla extract 1 teaspoon salt 1 teaspoon baking soda 1 teaspoon baking powder 2 cups semi-sweet chocolate chips