Preheat your oven to 350°F (or 180°C) and line two baking sheets with parchment paper.
In a glass bowl, melt the butter and chocolate chips together in the microwave.
In a mixing bowl, mix the sugar and eggs gently until bubbles begin to appear on top. Now, add in the vanilla extract and chocolate-butter mix and keep on mixing gently until it looks a bit shiny.
Mix in the flour, cocoa powder, baking soda, and salt until it is just combined. Now, fold in the chopped chocolate chunks, and place the ball in the freezer allowing the dough to rest for 25 minutes. The batter should look like a thickened fudge afterward.
Now, using a ¼ cup, scoop some dough into balls and place them on your lined baking sheets. After this, place the baking sheets with the rolled cookie dough in the freezer for 25 minutes.
Now, transfer the frozen dough balls to another lined baking sheet, making there be at least 2 inches of space between each of them.
Transfer the dough balls to your preheated oven, and bake for 10 minutes or until the edges start to set but the middle remains a bit doughy.
Set on a pan, and allow to cool. When ready to serve, sprinkle some flaky sea salt over the cookies.