Preheat the oven to 350F, and spray a large cast iron skillet with nonstick spray.

First make the brownie. In a microwave-safe medium bowl, melt together the chocolate chips, brown sugar, butter, and water for the brownie in 30 second increments, until smooth. Mix in the eggs, then the vanilla and dry ingredients. Set the brownie batter aside for now.

In a separate microwave-safe bowl, melt the butter for the cookie dough. Whisk in the white and brown sugar until well incorporated, then beat in the egg and vanilla until fluffy and lighter in color. Stir in the dry ingredients and finally the chocolate chunks.

Now you can pour the brownie batter into the skillet, and top it with a handful of roughly crushed Oreos. Top with dollops of the cookie dough, and more crushed Oreos on top.

Bake the brownie for 30-35 minutes, until a toothpick inserted in the center comes out mostly clean {aside from the melted chocolate chips}.

Let cool slightly then enjoy with ice cream!