Preheat oven to 350F degrees.
In a large mixing bowl or stand mix, cream together the butter and sugars until light and fluffy. Add in the egg and vanilla extract and mix until combined.
Next, add in the flour, cocoa powder, sea salt, baking powder and baking soda and mix until well combined.
Lastly, slowly pour in the buttermilk and mix while adding it in until the dough is soft.
Add in as much food coloring as needed and mix until the batter is the red color you desire!
From here, I find it easiest to refrigerate the dough for about 30 minutes to make it easier to scoop out. It's not required but certainly makes it easier.
When you're ready, scoop dough onto a lined baking sheet (either parchment paper or a silpat). I love using this cookie scooper because I find it easier to you. You can also just scoop out with a big spoon. I made large cookies and my batter came out to 12 cookies. Feel free to make them smaller!
I scooped out 6 cookies on the pan. They spread quite a bit while cooking so make sure to spread them out.
Bake for 8-11 minutes. For large cookies like mine, they took 11 minutes. If you're making them smaller, check them earlier. You want the tops set but soft. They'll continue to cook when you take them out so don't over bake!
Once done, cool on the baking sheet for about 10 minutes and then move to a wire rack to cool completely.