Preheat oven to 350 degrees F. Cream the butter and sugar together in a mixer on medium speed. Add the eggs one at a time, then the vanilla.
In a separate medium sized bowl, mix together the flour, dark cocoa powder, baking soda, baking powder, and salt. Gradually add the mixture to the wet ingredients in the mixer until well combined.
You can either mix in the chocolate chips and walnut now, then roll the dough into 1 inch balls, or roll the dough into one inch balls and press some chips and walnuts into the top (like I did for the cookies in the photo). Place dough balls 2 inches apart, as cookies will spread while baking.
Bake for 8-10 minutes. LET COOL before removing from the baking sheet.
** Nutritional information is an estimate and may vary.