In a medium bowl, combine the flour, cocoa powder, baking soda and salt with a whisk. Set aside.

In the bowl of a stand mixer, cream together the white sugar, brown sugar and melted butter on high. When that is well mixed, reduce the speed to low and add the egg and vanilla extract. When this is well combined, slowly add the set-aside flour mixture until just combined. Then fold in the chocolate chips using a spatula.

Using a tablespoon measuring spoon, measure out the dough. Place the cookie dough one inch apart. Press the top of each cookie with a spoon or the flat side of a knife to flatten the cookie, just a little. Sprinkle the top of each cookie with a little bit of sea salt.

Bake for 9-10 minutes, or until the cookie edges look browner than the dough. Remove from the oven, let cool on baking sheet for 10 minutes, then let them finish cooling on a baking rack.