Step 1: Preheat and Prepare

1. Preheat your oven to 350°F (175°C). Grease a 9×9-inch baking pan or line it with parchment paper for easy removal.
2. Set aside a handful of halved or crushed Oreos for topping.

Step 2: Make the Brownie Batter

1. In a large mixing bowl, whisk together the melted butter, granulated sugar, and brown sugar until smooth and creamy.
2. Add the eggs one at a time, whisking well after each addition. Stir in the vanilla extract.
3. In a separate bowl, sift together the flour, cocoa powder, salt, and baking powder. Gradually fold the dry ingredients into the wet mixture until just combined.
4. Gently fold in the chopped Oreos, being careful not to overmix.

Step 3: Assemble the Brownies

1. Pour half of the brownie batter into the prepared baking pan and spread it evenly with a spatula.
2. Arrange a layer of halved Oreos over the batter for a fun, hidden crunch.
3. Pour the remaining brownie batter over the Oreos and smooth the surface.
4. Scatter the reserved halved or crushed Oreos on top, pressing them slightly into the batter. If desired, sprinkle chocolate chips over the top for extra decadence.

Step 4: Bake

1. Place the pan in the preheated oven and bake for 30-35 minutes, or until a toothpick inserted into the center comes out with a few moist crumbs.
2. Avoid overbaking, as this can dry out the brownies.

Step 5: Cool and Serve

1. Allow the brownies to cool in the pan for 20 minutes before transferring them to a wire rack.
2. Once cooled, cut into 16 squares. Serve and enjoy!