1. Line an 8" square baking pan with parchment and grease the parchment with non-stick spray. Preheat the oven to 325*F.
2. Whisk together in a bowl the flour, salt and baking powder and set aside.
3. In a medium saucepan brown the butter over medium heat until golden brown. Immediately remove from the heat, transfer to a medium heat proof bowl and stir in the 4 ounces semisweet chocolate, the brown sugar, the cocoa, coffee and 4 teaspoons of water. Stir until smooth and shiny and then set aside to cool for ten minutes.
4. Add the beaten eggs and mix until smooth and shiny. Stir in the flour mixture and mix until completely combined.
5. Spread the batter into the prepared pan and top with the 2 ounces of chopped semisweet chocolate.
6. Bake for 40-45 minutes or until a toothpick inserted near the center comes out with fudgey crumbs.
7. Allow to cool completely before removing from the pan and slicing.