Preheat oven to 350°F. Line baking sheets with parchment paper.
In a large bowl, beat butter, granulated sugar, and brown sugar until light and fluffy.
Add eggs, red food coloring, and vanilla extract. Mix until smooth.
In a separate bowl, whisk together flour, cocoa powder, cornstarch, baking soda, and salt.
Gradually mix dry ingredients into wet ingredients until a thick dough forms.
Scoop large dough balls (about ¼ cup each) and place on baking sheet. Flatten slightly.
Bake for 10–11 minutes until edges are set and centers remain soft.
Cool completely before frosting.