Preheat your oven to 350°F (175°C) and line two baking sheets with parchment paper.

In a large bowl, cream softened unsalted butter with brown sugar and granulated sugar for about 3 minutes.

Add eggs one at a time and then add vanilla extract, mixing well.

Sift in cocoa powder, flour, baking soda, salt, and espresso powder (if using) and fold until just combined.

Fold in the chocolate chips evenly into the dough.

Drop rounded balls of dough onto the baking sheets, spacing them 2 inches apart.

Bake for approximately 10 minutes, edges set but centers soft.

Let cookies cool on the baking sheet for 5 minutes before transferring to a wire rack.