Preheat your oven to 350°F (176°C). Line two baking sheets with parchment paper or silicone baking mats.
In a medium bowl, whisk together the flour, cocoa powder, baking soda, and salt. Set aside.
In a large bowl, using a handheld mixer (or a stand mixer with a paddle attachment), beat the butter, granulated sugar, brown sugar, vanilla, and espresso powder together at medium speed until light and fluffy, 3 to 5 minutes.
Scrape down the sides and bottom of the bowl. Reduce the mixer speed to medium-low and add the eggs one at a time, beating until each is incorporated.
Turn the mixer to its lowest setting. Gradually add the dry ingredients to the butter mixture in three parts, mixing until just combined. The cookie dough will be pretty thick.
Switch to a spoon or spatula and fold in the chocolate chunks.
Using a medium cookie scoop or tablespoon measuring spoon, measure 2 heaping tablespoons (about 50g) of dough and roll it into a ball. Place the balls onto prepared baking sheets, spacing them about 2 inches apart to allow for spreading.
Bake one sheet at a time for 9 to 12 minutes or until the cookies have puffed up slightly and the tops look dry.
Let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.
