In a medium size bowl, sift the cocoa powder, flour, baking soda and salt. Mix well and set aside.
In a large bowl, cream the butter, sugar and brown sugar
Beat the eggs in, adding one egg at a time.
Stir in the vanilla
Gradually add in the dry ingredients, making sure to mix well
After the batter is fully incorporated, stir in the chocolate chips. Set the batter in the fridge to cool
Preheat the oven to 350 F. Scoop the batter into heaping tablespoons and place on a cooled, ungreased cookie sheet about 2 inches apart. Use silicone baking mats or parchment paper for best results. Add extra chocolate chips, M&M candies or sprinkles if desired. Bake for 10-12 minutes
Remove cookies from oven, and let cool slightly. Then, place on cooling rack or cool surface to cool completely.