Preheat oven to 375° F.
Cream together the butter, granulated sugar and brown sugar.
Add the egg and vanilla. Mix until light in color and creamy.
Add in the dry ingredients (flour, cocoa, baking soda and salt), mix into the dough. Mix until completely combined. The dough will be soft.
Mix in the red food coloring until you’ve achieved your desired color.
Scoop the cookie dough out into 1 1/2 tbsp portions (#40 scoop).
Roll first in granulated sugar and then in the powdered sugar/cornstarch mixture and then arrange on a parchment or silicone lined cookie sheet.
Repeat with remaining dough.
Bake at 375° F for 7-10 minutes, until the cookies flatten, spread and begin to crackle.
Allow the cookies to cool on the pan for 5 minutes before transferring to a wire cooling rack.