01 - Whisk together flour, cocoa powder, baking powder, and salt in a medium bowl until thoroughly mixed.
02 - Beat sugar and vegetable oil with an electric mixer until blended, then add eggs one at a time, mixing well after each addition; incorporate vanilla extract.
03 - Gradually add dry ingredients to wet mixture, stirring until just combined forming a sticky dough.
04 - Cover the dough bowl with plastic wrap and refrigerate for at least two hours until firm.
05 - Preheat oven to 350°F (175°C) and line two baking sheets with parchment paper.
06 - Scoop tablespoon-sized portions of dough, roll into balls, and coat thoroughly in powdered sugar.
07 - Place the coated dough balls on baking sheets spaced about 2 inches apart.
08 - Bake for 10 to 12 minutes until cookies puff up and develop a crackled surface but remain soft inside.
09 - Allow cookies to cool on baking sheets for 5 minutes before transferring to a wire rack to cool completely.