01 - Whisk together the flour, cocoa powder, baking powder, and salt in a medium bowl.
02 - In a large bowl, blend the sugar and vegetable oil. Beat in eggs one at a time, then stir in vanilla extract.
03 - Gradually incorporate the dry mixture into the wet mixture until a sticky dough forms.
04 - Cover and refrigerate the dough for at least one hour until it firms up.
05 - Preheat the oven to 350°F (175°C) and line baking sheets with parchment paper.
06 - Scoop heaping tablespoons of dough, roll into balls, then coat them thoroughly in powdered sugar.
07 - Place the coated dough balls two inches apart on the prepared baking sheets.
08 - Bake for 10 minutes until the cookies are set but remain soft in the center.
09 - Allow cookies to cool on the baking sheets for five minutes, then transfer to a wire rack to cool completely.