First, melt the butter in a medium-sized mixing bowl.
Once the butter is melted, add in the cocoa powder and vanilla extract and stir it until it’s smooth and combined.
Combine the butter mixture with the brown sugar and white sugar in the bowl of your stand mixer with the paddle attachment attached and mix on medium speed until light and fluffy. About 2 minutes.
Next, add in the eggs and mix on medium speed for 1-2 minutes until it’s light and airy.
While mixing on low, add in the flour, salt, baking soda, cornstarch, and chocolate chips. Mix dough just enough until everything is combined.
Chill dough in the fridge until it firms up, at least 1 hour.
Turn oven on to 350° and prepare a lined baking sheet.
Bake the cookies for about 10 minutes, or until they are no longer shiny in the center and the edges are set.
Allow the cookies to cool for 5 minutes on the baking sheet.
Transfer the cookies to a cooling rack to allow them to cool all the way.
