In a small bowl, combine the flour, cocoa, baking soda, and salt. In a large bowl, use an electric mixer to beat together sugars, butter, and vanilla. Add the eggs, one at a time. Then gradually stir in the flour/cocoa mixture. Fold in the chocolate chunks and Halloween Oreos. Save a few chocolate chunks and Oreos for sprinkling on the tops of the cookies after they come out of the oven.