Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a microwave-safe bowl, combine the semi-sweet chocolate chips and unsalted butter. Microwave in 20-second intervals, stirring in between, until melted and smooth. Let it cool slightly.
In a large mixing bowl, beat together the eggs, granulated sugar, and vanilla extract until well combined and slightly frothy.
Stir the melted chocolate mixture into the egg mixture until fully incorporated.
In another bowl, whisk together the all-purpose flour, cocoa powder, baking powder, and salt. Gradually fold this dry mixture into the wet mixture until just combined.
Chill the cookie dough in the refrigerator for about 30 minutes to firm up.
Once chilled, scoop tablespoon-sized amounts of dough and roll them into balls. Coat each ball in granulated sugar, then roll them in powdered sugar until well dusted.
Place the cookie dough balls on the prepared baking sheet, leaving space between them for spreading.
Sprinkle a few sea salt flakes on top of each cookie.
Bake in the preheated oven for 10-12 minutes, or until the edges are set but the centers look slightly soft.
Allow the cookies to cool on the baking sheet for 5 minutes before transferring to a wire rack to cool completely.
Notes
Serve the cookies on a decorative plate and sprinkle some additional sea salt flakes over them just before serving for that extra touch.