In a medium mixing bowl whisk together the all purpose flour, cocoa powder, baking powder, baking soda and salt. Set aside.
In a stand mixer fitted with a paddle attachment, or with a hand mixer, over medium speed beat together the softened butter, granulated sugar, and brown sugar for about 5 minutes until well creamed scraping the bowl.
Next, beat in the whole egg and egg yolk. Then add in the vanilla and food coloring. Mix until combined, scraping the sides. Once combined, mix in the buttermilk and vinegar.
Slowly add the dry ingredients into the wet ingredients over low speed, just until combined.
Cover the bowl of dough with plastic wrap and chill in the refrigerator for at least 1-2 hours. If you leave the dough in the fridge longer or overnight, let it warm up no longer than 30 minutes. It's going to be hard to scoop, but needs to be cold to get good cracks.
Preheat the oven to 350°F. Line baking sheets with parchment paper. Fill one bowl with granulated sugar and one for powdered sugar for rolling.
Scoop the stiff, chilled dough into 2 tablespoon sized portions and roll into balls. Once all balls are made, roll each one in the granulated sugar and then two coats of powdered sugar. Stir the powdered sugar if it becomes compact. Place 2 ½ inches apart on the baking sheets.
Bake one sheet at a time for 11-13 minutes. Let them cool on baking sheet for 5 minutes before moving to a cooling rack.. Makes 32 cookies.