Line a 9x13 baking pan with foil. Preheat oven to 350ºF
Combine cocoa powder and flour in a medium bowl, set aside.
Using a mixer, mix in butter and sugar on high speed until light and fluffy. Beat in the eggs, one at a time until smooth and glossy. Add salt and vanilla. Stir in walnuts and spread into prepared pan.
Bake 45-50 minutes or until toothpick inserted in center comes out bearing some moist crumbs.
Cool in the pan on a wire rack. Discard the foil. Cut into 2-in squares.
Recipe by Flavor and Friends at http://flavorandfriends.com/dutch-cocoa-brownies-with-walnuts/