Place the chopped semisweet baking chocolate in a microwave-safe bowl. Melt for about 10-15 seconds at a time, stirring in between to avoid scorching. Once it’s well melted, set it aside to cool. You don’t want it to be hot when adding it to the eggs or it might cook the eggs.
Use a fine-mesh sieve to sift the flour, cocoa powder, espresso powder, baking powder, and salt into a bowl. Use a whisk to mix the dry ingredients and set aside.
In a large mixing bowl, beat the eggs, granulated sugar, and brown sugar until well combined. Add the vanilla extract and melted butter, mixing until smooth.
Gradually add the melted chocolate to the egg mixture, stirring constantly to combine.
Slowly incorporate the dry ingredients into the wet mixture, stirring until just combined. Fold in the semisweet chocolate chips.
Cover the bowl with plastic wrap and refrigerate the dough for at least 30 minutes.
Preheat the oven to 350°F (175°C) and line a baking sheet with parchment paper.
Scoop the dough using a cookie scoop or spoon and place on the prepared baking sheet, spacing the cookies about 2 inches apart.
Bake for 10-12 minutes or until the edges are set but the centers are still slightly soft. Allow the cookies to cool on the baking sheet for a few minutes before transferring to a wire rack to cool completely.