1. Whisk the cocoa powder, flour, baking powder, and salt in a bowl until evenly combined.

2. In a separate large bowl, mix the granulated sugar and vegetable oil until smooth and glossy.

3. Add the eggs one at a time, mixing well after each addition, then stir in the vanilla extract.

4. Add the dry ingredients to the wet mixture and stir until a thick chocolate dough forms.

5. Cover the bowl and chill the dough for at least 2 hours, or until firm enough to scoop.

6. Preheat the oven to 350°F and line baking sheets with parchment paper.

7. Scoop the chilled dough into small balls and roll each one generously in powdered sugar.

8. Arrange the dough balls on the prepared baking sheets, leaving space between each cookie.

9. Bake for 10 to 12 minutes, until the tops are crackled and the edges are set.

10. Let the cookies cool on the baking sheet for a few minutes, then transfer them to a wire rack.