In a large mixing bowl, combine unsweetened cocoa and granulated sugar.
Add vegetable oil and eggs to the cocoa mixture. Mix until blended.
Add the vanilla extract, flour, baking powder, and salt. Mix until the dough is combined.
Place the dough in an airtight container and refrigerate for 2 to 3 hours before preparing cookies. Ideally, the dough should be refrigerated overnight.
Preheat oven to 350 degrees. Line baking sheets with parchment paper.
Take 2 teaspoons of dough and roll it into a ball.
Drop the dough ball into the powdered sugar.
Place the sugar-covered ball on the parchment-lined baking sheet lined with parchment paper.
Repeat with the remaining dough, spacing cookies 2 inches apart on the baking sheet.
Bake at 350°F for 10 to 12 minutes.
Allow the cookies to cool on the baking sheet for 1 minute before transferring them to a wire rack.