In a medium bowl, whisk cocoa, flour, baking powder and salt together until well combined.

In a large bowl, whisk together vegetable oil, eggs, and vanilla. Gradually add in cocoa mixture, stirring with a rubber spatula until well incorporated. Repeat until all of dry ingredients are thorougly mixed with the rest of the cookie batter. It will be dark and sticky.

Cover dough with plastic wrap and refrigerate from 4 hours to overnight.

Preheat oven to 350 degrees F.

Line a baking sheet with parchment paper. Spray a small cookie scoop (about 2 tablespoon in size) with spray oil, scoop out dough and roll in powdered sugar in a bowl or plate. Place cookies 2 inches apart on parchment lined baking sheet.

Keep dough in fridge between batches.

Bake for 11-13 minutes, tops should be cracked.

Let cookies cool for 3 minutes on sheet, then let cool on a wire rack.

Store in an airtight container for 3 days.