• Preheat the oven to 350° and have ready a greased 9x13" brownie pan or a 9x13" casserole dish.

For the Brownie Layer:

• In a medium-sized mixing bowl, whisk together flour, sugar cocoa powder, baking soda, and salt. Add the butter, egg, and vanilla, and mix on medium speed using a handheld mixer until well combined. The mixture may appear powdery and dry at first -- just keep mixing. Scrape down the sides of the bowl, add the chocolate chips, and mix once more.
• Transfer the brownie batter to the prepared dish and gently pat it across the bottom to cover.

For the Cookie Layer:

• In a large mixing bowl, whisk together the flour, granulated sugar, brown sugar, baking soda, and salt. Add the butter, egg, and vanilla, and mix on medium speed using a handheld mixer (with clean beaters) until well combined. Again, the mixture may appear powdery and dry at first -- just keep mixing. Scrape down the sides of the bowl, add the chocolate chips, and mix once more.
• Transfer scoops of the cookie dough to the prepared dish and gently pat across the surface of the brownie batter layer to slightly smooth it out.
• Bake for 25 minutes for a gooey center or 30 minutes for a more well-done Brookie. Transfer to a cooling rack for 20-25 minutes. Cut into squares, serve and enjoy.