01 - Whisk together flour, cocoa powder, baking powder, and salt in a medium bowl.
02 - Beat sugar and vegetable oil until well combined. Add eggs one at a time, mixing thoroughly after each addition, then incorporate vanilla extract.
03 - Gradually stir dry ingredients into wet mixture until a thick dough forms.
04 - Cover dough and refrigerate for at least 2 hours until firm.
05 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
06 - Scoop tablespoon-sized portions and roll into balls.
07 - Roll each dough ball generously in powdered sugar until fully coated.
08 - Place coated balls 2 inches apart on prepared sheets and bake for 11 to 13 minutes until set but soft in centers.
09 - Allow cookies to cool on baking sheets for 5 minutes, then transfer to wire rack to cool completely.