Preheat oven to 350° F. Prepare baking pans with parchment paper or silicone baking mats.
In a bowl, combine flour, cocoa powder, baking soda, baking powder, and salt. Whisk to combine and set aside.
In a large mixing bowl, add butter, granulated sugar, and brown sugar. Cream on medium speed using an electric hand mixer.
Add in egg, vanilla extract, and red gel food coloring and continue to mix until smooth.
Add half of the flour mixture. Mix on low speed until combined. Pour in buttermilk and continue to mix on low until combined and smooth.
Add the remaining flour mixture and mix until the dry ingredients are fully incorporated. Scrape the sides and bottom of the bowl to ensure all the ingredients are well mixed.
Use a large cookie scoop (3 tbsp) to portion the batter onto the prepared baking pans. Allow space between the cookies for spreading.
Bake for approximately 12-13 minutes until the cookies are puffed up and set.
Remove the pan from the oven and allow the cookies to cool on the pan for 1-2 minutes. Transfer the cookies to a wire baking rack to cool completely.