Preheat the oven to 350°. Using a stand mixer, cream together the butter and sugars until light in color and fluffy in texture. Add in the eggs, corn syrup, and vanilla. Mix until thoroughly combined. Next, add the flour, cocoa, cornstarch baking soda, and salt. Mix until your chocolate cookie dough forms. The dough will be soft. Fold in the chocolate chips.
Divide the dough out into 12 equal portions, just under 1/2 cup measuring cup each. Roll each portion into ball then flatten slightly with the palm of your hand so it looks like a hockey puck before arranging on a parchment paper cookie tray. Place 6 cookies per tray.
Bake at 350° for 15-17 minutes. The cookie should start to crack and crinkle, it will spread slightly and the centers of the cookie should no longer look glossy or wet before taking them out of the oven.