Add cooled melted butter, granulated sugar and brown sugar to the stand mixer bowl and beat with the paddle attachment for 2 minutes until lighter in color.
Add the egg, egg yolk, vanilla extract, liquid red food color and continue beating for another 2 minutes until fluffy.
In another mixing bowl, sift together the flour, cocoa powder, baking soda, and baking powder. Stir in the kosher salt and give it a good mix to distribute. Add the flour mixture to the wet ingredient mixture in the stand mixer bowl, stir until incorporated. Stop the mixer and scrape down the sides and bottom of the bowl as necessary.
Add the chocolate chips and stir to incorporate. Stop the mixer and scrape down the bowl with a spatula and give it another good mix as needed. Cover and refrigerate the dough for 30 minutes.
Portion the cookie dough with a large cookie scoop and place them on a parchment lined baking sheet. Refrigerate for at least another 30 minutes. (Optional: If you want the cookie to be rounder, roll the portioned dough into balls.)
Preheat the oven to 350°F.
Place 6 dough balls on a baking sheet, about 2 inches apart, and bake 1 batch at a time for 14 - 15 minutes, until the outer edges of the cookies look crispy but the middle is still soft and slightly undercooked. The cookies will finish baking from the residual heat once you remove them from the oven.
Allow the cookies to cool on the baking sheet for 10 minutes before removing them to a wire rack to cool completely.