Preheat your oven to 325 degrees Fahrenheit.
In a large mixing bowl or in the bowl of a stand mixer, cream together the softened butter, brown sugar, and granulated sugar until light and creamy.
Add the egg and vanilla into the cookie dough and beat again until just combined.
Add the flour, cocoa powder, baking soda, and salt and beat until just combined. Do not overmix.
Use a wooden spoon or rubber spatula to mix in the chocolate chips until evenly distributed.
Scoop the cookie dough onto an ungreased cookie sheet using a #24 cookie scoop (about 2 ½ Tablespoons each).
Bake in the preheated oven for 12–15 minutes or until the edges set but the centers are still soft.
Allow the cookies to cool on the baking sheet for a few minutes. After 5 minutes, transfer the cookies to a wire rack to cool the rest of the way.
Serve and enjoy!