Preheat the oven to 350°F and line two cookie sheets with parchment paper. Set aside.
In the bowl of a stand mixer, cream together the butter and sugar until light and fluffy, then mix in the egg and vanilla extract until combined.
In a separate medium mixing bowl, whisk together the flour, baking soda, salt and cocoa powder.
Add the dry ingredients to the butter mixture and mix to combine. The dough will look dry and crumbly at this point.
Finally, add the buttermilk and red food coloring to this mixture. At this point, the batter should no longer be dry and should have a much smoother consistency.
Using a tablespoon-sized cookie scoop, scoop the batter onto your prepared cookie sheets and bake in the preheated oven for 12 minutes (or until the cookies look set, not wet, but not brown), rotating the trays halfway through.