In a medium bowl, mix together cocoa, white sugar, and vegetable oil. Beat in eggs one at a time, then stir in the vanilla. Combine the flour, baking powder, and salt; stir into the cocoa mixture. Cover dough, and chill for at least 4 hours.

Preheat oven to 350 degrees F (175 degrees C). Line cookie sheets with parchment paper.

Roll dough into one inch balls (#50 size scoop). Coat each ball in confectioners sugar before placing onto prepared cookie sheets. Hint: Dip top have of ball in granulated sugar first then in powdered sugar. One tester says the gran sugar creates a crisp surface as it cooks and makes the cracks more pronounced.

Bake in preheated oven for 10 to 12 minutes. Let stand on the cookie sheet for a minute before transferring to wire racks to cool.

Make ahead: Freeze the balls. Dip in sugar when ready to bake.