Preheat oven to 300°F
In a large mixing bowl, cream together butter, brown sugar, granulated sugar and vanilla. Add eggs one at a time
In a small bowl, mix together unsweetened cocoa powder, salt, baking soda and flour
Gradually add the flour mixture to the butter mixture, mixing as you add. The batter will be thick like brownie batter
Mix in chocolate chips
Spoon out 1" cookie balls on a baking sheet 3" apart
Place a couple of chocolate chips on top of each cookie ball
Bake for 16 minutes