In a large bowl, mix the cocoa powder, granulated sugar, and oil until combined and rich-looking.
Beat in the eggs one at a time, then stir in the vanilla.
In a separate bowl, whisk the flour, baking powder, and salt. Slowly stir this into the wet ingredients.
Cover the dough and chill for at least 4 hours—or overnight if you can resist.
Preheat your oven to 350°F (175°C). Line baking sheets with parchment paper.
Scoop chilled dough into tablespoon-sized balls, roll in powdered sugar until fully coated, and space them 2 inches apart on the sheet.
Bake for 10-12 minutes until the edges are set but the centers are still soft. Cool on the sheet for 5 minutes before transferring.