Preheat oven to 350 degrees and line a baking sheet with parchment paper.
Mix together the flour, cocoa powder, black cocoa powder, baking soda and salt.
In a separate bowl, beat the butter, sugar, dark brown sugar and vanilla.
Add the dry ingredients and beat until combined.
Roll into balls and place on prepared cookie sheet. Use the bottom of a cup to flatten out the dough balls. Sprinkle with mini chocolate chips and sea salt.
Bake for 12 - 14 minutes, until the tops start to crack. Move onto a cooling rack.
