Pour dry brownie mix into a large bowl. Add in cocoa powder and mix until combined. Prepare brownies as directed on the box, replacing the water with coffee, and adding in vanilla, dark chocolate chips and sea salt. Pour batter into an 8x8 or 9x9 inch baking pan and bake according to package directions (look for the directions specifically for a smaller pan). Remove from oven and allow to cool prior to slicing. Serve and enjoy.