Preheat the oven to 350ºF (180ºC). Butter an 8”x8” metal cake pan.
Heat a medium saucepan over low heat, add the butter and allow to melt. Once melted, whisk in the chocolate and allow to melt. Remove from the heat and transfer to a medium mixing bowl.
One at a time whisk in the cocoa, sugar, eggs, 2 tablespoons of water, vanilla and flour followed by the cinnamon, ginger, nutmeg and cayenne. Stir in the walnuts.
Evenly pour the batter into the prepared pan. Bake until the brownies are still gooey but cooked through, about 40 to 45 minutes. A toothpick inserted into the middle should come out just about clean.
Let cool for about 1 hour then cut the brownies into 9 squares and serve at room temperature.