01 - Whisk together flour, cocoa powder, baking powder, and salt in a medium bowl.
02 - Beat sugar and vegetable oil in a large bowl until combined. Add eggs one at a time, beating after each addition. Stir in vanilla extract.
03 - Gradually incorporate dry ingredients into wet mixture, stirring until a thick dough forms.
04 - Cover dough and refrigerate for a minimum of 2 hours until firm.
05 - Preheat oven to 350°F. Line two baking sheets with parchment paper.
06 - Scoop tablespoon-sized portions of dough and roll each into a ball.
07 - Roll dough balls generously in powdered sugar until fully coated.
08 - Place sugar-coated balls 2 inches apart on prepared baking sheets. Bake 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.