In a medium-sized bowl, whisk together the all-purpose flour, cocoa powder, baking soda, and salt. Set aside.
In a separate large bowl, cream together the unsalted butter, granulated sugar, and brown sugar until light and fluffy.
Add the eggs one at a time, beating well after each addition. Stir in the vanilla extract.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Be careful not to overmix.
Fold in the dark chocolate chunks until evenly distributed throughout the dough.
Cover the dough and refrigerate for at least 1 hour or overnight to allow the flavors to meld and the dough to firm up.
Preheat the oven to 350°F (175°C). Line a baking sheet with parchment paper.
Use a cookie scoop or tablespoon to portion out the dough onto the prepared baking sheet, leaving space between each cookie.
Bake for 10-12 minutes, or until the edges are set and the centers are slightly soft. The cookies will firm up as they cool.
Remove from the oven and let the cookies cool on the baking sheet for 5 minutes before transferring them to a wire rack to cool completely.