Mix flours, baking soda and salt together. Beat butter, brown and white sugars together until fluffy, add eggs and vanilla and mix. Then combine the flour and sugar mixture, plus cocoa power. Roll in tablespoon full balls and roll into powdered sugar, then drop onto greased cookie sheets.
*** I double the recipe because while 15 cookies is fabulous, three dozen is even more fabulous. These are my favourite, favourite cookies. They taste like chocolate cake. Bake at 350 degrees for 9 to 11 minutes, depending on whether you are using convection or not.