Preheat the oven to 350 degrees F. Spray a 9X13 baking pan with a non stick cooking spray.
In a large mixing bowl, thoroughly combine the butter, eggs, sugars and vanilla extract until they are well mixed.
Then slowly stir in the cocoa powder, flours, salt and baking powder. Mix these ingredients in by hand and be careful not to over mix these ingredients.
Spread the batter into the 9X13 pan.
Bake for 20-25 minutes until a toothpick inserted into the brownies comes out clean be careful not to over bake or the brownies will be dry.
Prepare the fudge topping by heating up the heavy whipping cream in a sauce pan on medium heat. Add the chocolate chips and keep stirring until completely melted and smooth.
Pour on top of brownies and smooth it out using a spatula.
Sprinkle the chopped walnuts on top and refrigerate for 1 hour to allow the topping to set.
Then cut, serve and enjoy!