In a large mixing bowl, cream together softened butter, granulated sugar, and brown sugar using an electric mixer on medium speed until light and fluffy (about 2–3 minutes).
Add eggs, one at a time, mixing well after each addition. Stir in vanilla extract until fully combined.
In a separate bowl, whisk together the all-purpose flour, cocoa powder, baking soda, and salt.
With the mixer on low speed, gradually add the dry ingredients to the butter mixture. Beat until just combined.
Use a rubber spatula to scrape down the sides of the bowl and ensure everything is evenly mixed.
Gently fold in the chocolate chips until evenly distributed.
Cover the dough and refrigerate for at least 2 hours (or overnight for deeper flavor).
Preheat the oven to 350°F (175°C) and line baking sheets with parchment paper or silicone mats.
If the dough is too firm, let it rest at room temperature for 10–15 minutes until scoopable.
Scoop the dough using a cookie scoop or rounded tablespoon and place balls 2 inches apart on the prepared baking sheets.
Bake for 8–10 minutes, until the edges are set and the centers are still soft.
Remove from the oven and let cookies cool on the baking sheets for 3–5 minutes.
Transfer cookies to a wire rack to cool completely.