In a medium bowl, whisk together your cocoa powder, sugar and olive oil. Beat in your eggs one at a time, until fully incorporated. Stir in your vanilla extract.
In a separate medium bowl, whisk your flour, baking powder, and salt. Stir the dry ingredients into the wet mixture just until a dough forms. Cover bowl with wrap and refrigerate for at least 4 hours or overnight.
When your are ready to bake, preheat your oven to 350 degrees F. Place your icing sugar into a bowl. Line a large cookie sheets with parchment paper. Roll your dough into a ball that is roughly 1.5 tbsp in size.