Whisk together the flour, cocoa powder, baking powder, and salt.
Beat the butter and granulated sugar until light and fluffy.
Mix in the eggs one at a time.
Stir in the vanilla extract.
Gradually add the dry ingredients until combined.
Fold in the chocolate chips if using.
Cover the dough and chill for at least 2 hours.
Preheat the oven to 350°F (175°C).
Line a baking sheet with parchment paper.
Scoop tablespoon-sized portions of dough.
Roll each dough ball generously in powdered sugar.
Arrange the cookies 2 inches apart on the baking sheet.
Bake for 10–12 minutes until the tops crack.
Let the cookies cool on the baking sheet for 5 minutes.
Transfer to a wire rack to cool completely.