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 mixter. Cover dough, and chill for at least 4 hours.
Preheat the oven to 350 degrees F. Line cookie sheets with parchment paper. Roll dough into one inch balls I like to use a number 50 size scoop. Coat each ball in confectioner's sugar before placing onto prepared cookie sheets.
Bake in a preheated oven for 10 to 12 minutes. Let stand on the cookie sheet for a minute before transferring to wire racks to cool.