Cream the Butter and Sugars: In a large bowl, use a handheld or stand mixer fitted with a paddle attachment to beat the softened butter, granulated sugar, and brown sugar on medium-high speed for about 2–3 minutes, until the mixture is fluffy and noticeably lighter in color.
Add the Egg and Vanilla: Add the room-temperature egg and vanilla extract to the butter mixture, then beat on high speed until everything is well combined. Scrape down the sides and bottom of the bowl as needed to ensure the mixture is evenly incorporated.
Combine the Dry Ingredients: In a separate bowl, whisk together the all-purpose flour, natural cocoa powder, baking soda, and salt until evenly combined.
Make the Cookie Dough: With the mixer running on low speed, gradually add the dry ingredients to the wet mixture. Beat just until combined, then mix in the semi-sweet chocolate chips. The finished dough will be thick and very sticky.
Chill the Dough: Cover the dough tightly and refrigerate it for at least 3 hours and up to 3 days. Do not skip this chilling period, as the dough needs to firm up before it can be easily scooped and rolled.
Soften the Chilled Dough: Remove the dough from the refrigerator and let it stand at room temperature for 10 minutes. If it has been refrigerated for longer than 3 hours, allow it to sit for about 20 minutes instead. This makes the chilled dough easier to scoop and shape. Prepare the Oven and Baking Sheets: Preheat the oven to 350°F (177°C). Line large baking sheets with parchment paper or silicone baking mats and set them aside.
Shape and Coat the Cookies: Scoop approximately 1½ tablespoons of dough per cookie and roll each portion into a ball. Lightly roll each dough ball in the granulated sugar first, then coat it generously with confectioners’ sugar. Arrange the coated dough balls on the prepared baking sheets, leaving about 3 inches of space between them. Bake the Cookies: Bake at 350°F (177°C) for 11–12 minutes, or until the edges look set while the centers still appear soft.
Encourage Spreading if Needed: Check the cookies around 9 minutes. If they are not really spreading, remove the baking sheet from the oven and lightly bang it against the counter 2–3 times to help initiate spreading. Return the cookies to the oven and continue baking.
Cool on the Baking Sheet: Let the freshly baked cookies cool on the baking sheet for 5 minutes. They will slightly deflate as they cool.
Finish Cooling: Transfer the cookies to a cooling rack and allow them to cool completely before serving or storing.
Store the Cookies: Keep the cooled cookies covered at room temperature for up to 1 week.
