In a medium bowl, whisk together flour, cocoa powder, salt and baking soda. In a large bowl using either a hand or stand mixer, beat softened butter and granulated sugar together until fluffy.
Add in egg and vanilla extract, beat until smooth. Add the dry ingredients into the mixture in three additions and beat until all of the flour is incorporated. Add in red food coloring and beat until until fully red.
Cover and refrigerate dough for at least one hour. Preheat oven to 350 F. Place powdered sugar into a shallow dish. Roll cookie dough into balls and roll into the powdered sugar.
Place cookies 2-inches apart onto ungreased baking sheets. Bake for 10-12 minutes.
