1. In a mixing bowl, combine unsweetened cocoa powder, granulated sugar, and vegetable oil until well blended.

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

3. In a separate bowl, whisk together the all-purpose flour, baking powder, and salt.

4. Gradually add the dry ingredients to the wet mixture, stirring until the dough is smooth and fully combined.

5. Cover the dough and refrigerate for several hours or overnight to allow it to firm up.

6. Preheat the oven to 350°F (175°C) and line a baking sheet with parchment paper.

7. Scoop out portions of the chilled dough and roll them into small balls.

8. Roll each dough ball first in granulated sugar and then in powdered sugar to ensure a thick coating.

9. Place the coated dough balls onto the prepared baking sheet, leaving space between each for spreading.

10. Bake in the preheated oven for 10 to 12 minutes, or until the cookies have puffed up and developed cracks.

11. Remove from the oven and allow the cookies to cool on the baking sheet for a few minutes before transferring them to a wire rack.

12. Let them cool completely and enjoy, or store in an airtight container at room temperature for up to a week.