Preheat the oven to 350 degrees F. Line two baking sheets with parchment paper and set aside.
In a medium-sized bowl, whisk together the flour, cocoa powder, baking soda, baking powder, and kosher salt. Set aside.
In the bowl of a stand mixer, cream the butter and sugar together until light and fluffy. Add the egg and vanilla extract, mixing to combine.
In a couple of batches, add the dry ingredients to the wet. Add the chocolate chips/chunks, and mix to distribute them evenly throughout the dough.
Using a cookie scoop, or by rolling tablespoons of dough into balls, place the dough onto the prepared cookie sheets, leaving a couple of inches between each dough ball.
Sprinkle each dough ball with kosher or sea salt.
Bake for 11-12 minutes, or until the cookies are just done. Allow them to cool on the cookie sheet for 5 minutes before removing them to wire racks to finish cooling completely.