Coarsely chop the chocolate and melt it together with the butter in a saucepan over medium heat while stirring constantly. Remove from the heat, pour into a mixing bowl. Let cool for 8-10 minutes.
Preheat your oven to 350°F (180°C) and spray a 9-inch (or 8-inch) square pan with cooking spray and line it with parchment paper leaving an overhang.
Add the sugar to the chocolate mixture and whisk until well incorporated. Add the eggs, one at a time. Whisk in the vanilla extract.
Add the flour, Dutch-process cocoa powder, and salt and gently fold them in. Mix only until everything is incorporated and the dry ingredients are wet and no clumps remain. Fold in chocolate chips.
Spread half of the batter into your prepared pan. Top with a layer of Oreo Cookies and spread the remaining batter on top of the cookies. Sprinkle crushed Oreos on top.
Bake for 30 minutes or until a toothpick comes out with only a few moist and fudgy crumbs attached.
Let the brownies cool in the pan on a wire rack to room temperature.
