Whisk together flour, cocoa powder, baking powder, baking soda, and salt.
Cream butter and sugar until fluffy, then mix in egg, vanilla, vinegar, and red food coloring.
Gradually add dry ingredients and buttermilk, alternating between the two. Mix until combined.
Chill the dough for at least 1 hour.
Preheat oven to 350°F (175°C) and line baking sheets with parchment paper.
Roll dough into 1-tablespoon balls, coat in powdered sugar, and place on baking sheets.
Bake for 10-12 minutes until cracks appear. Let cool before serving.