Place melted butter and sugars in the bowl of a stand mixer and mix on low speed using the paddle attachment until smooth.
Then add in egg and vanilla extract and mix on medium speed until combined. Mix in baking soda, salt, and cocoa powder and then slowly mix in the flour and continue to mix until the batter is smooth and comes together. Slowly mix in the chocolate chips.
Scoop the dough onto a baking sheet, and then place in refrigerator and let chill for 1 hour.
Bake for 10 minutes or until the edges are lightly golden.