Sift together the flour, baking powder, and sea salt in a small bowl.
In a large bowl, whisk together the eggs, vanilla extract, and sugar.
In a small saucepan, over low heat, melt together the bittersweet chocolate, butter, and espresso powder.
Stir continuously until everything is melted together.
Let cool for five minutes.
Whisk the melted chocolate into the egg mixture until combined.
Add in the dry ingredients slowly.
Fold in the chocolate chips.
Chill the dough for at least an hour in the refrigerator, up to two days.
Cover a baking sheet in parchment paper.
Place the dough 1" apart on the baking sheet in rounded tablespoons.
Bake for 10-15 minutes at 325F. The cookies are done when the tops begin to appear cracked.
Remove from the oven and top with sea salt when cool.
We used Medaglia D'Oro instant espresso.