Preheat oven to 350 degrees.
In a small sauce pan, melt the butter over medium-low heat.
Add the chocolate chips and stir until melted.
Remove from the heat and stir in both sugars and mix well.
Cool slightly (just a minute or two).
Add the egg and vanilla. Stir well
Add the flour, cocoa, baking soda, and salt (not sea salt) to the sauce pan and stir well.
Scoop the dough by rounded tablespoon onto a parchment lined (or greased) baking sheet.
Sprinkle with sea salt.
Bake for 9-10 minutes. The cookies will be crinkly on top and a bit gooey in the middle, but they will continue to bake on the pan as they rest.
Let sit on the pan at least 10 minutes to finish baking before removing.