• Preheat oven to 350F. Grease and line a 9" x 9" baking dish. Set aside.

For the Cookie Layer

• In a large mixing bowl, combine the sugars and butter until light and fluffy, 2 minutes. Add the egg and vanilla and beat until incorporated.
• In a separate bowl, stir together the flour, baking soda and salt. Add to the butter mixture and beat until well incorporated. Add chocolate chips.
• Press the chocolate chip cookie dough into the prepared baking dish. Top with a layer of OREO cookies (approximately 16). Set aside.

For the Brownie Layer

• In a large mixing bowl, combine the sugar and butter until light and fluffy, 2 minutes. Add the eggs and vanilla and beat until incorporated.
• In a separate medium-sized bowl, combine the cocoa powder, flour, salt and baking powder. Stir until mixed. Add half of the dry ingredients into the butter-sugar mixture, beat well, then add remaining half.
• Fold the brownie batter out overtop of the cookie dough mixture. Crush the remaining oreos and top the mixture with them.
• Place in oven and bake for 40-50 minutes until an inserted toothpick comes out clean (start checking at the 35 minute mark).