Preheat oven to 335F/170C. Line baking sheet with parchment paper.
Sift cocoa powder with sugar, salt, baking powder, and baking soda. Keep aside.
Add flour to a different bowl, make sure that the bowl is heat resistant.
In a saucepan, heat the butter until it starts to boil, remove immediately from heat and pour in one go over the flour. Mix the flour with the hot butter until combined. Be careful in this step.
Beat the egg with vanilla and add to the flour mixture, add the cocoa mixture and mix well.
Add the chocolate chip too and don’t over mix. Cover and chill for 20 minutes.
Take 3 tablespoon from the dough and form a ball. Now tear the ball from the middle creating two balls with jagged edges from one side.
Gently smush both balls together jagged side up. Place on baking sheet and bake for 11 to 13 minutes.
Cool on a cooling rack, when the cookies are completely cool store in airtight container.