Preheat your oven to 350°F (175°C) and line your baking sheets with parchment paper.
In a large mixing bowl, whisk together the granulated sugar and vegetable oil until well combined.
Beat in the eggs one at a time, followed by the vanilla extract, mixing until smooth.
In another bowl, sift together the flour, cocoa powder, baking powder, salt, and baking soda.
Gradually add the dry ingredients to the wet mixture, mixing until a soft dough forms.
Chill the dough in the refrigerator for about 15 minutes to make it easier to handle.
Once chilled, use a cookie scoop or spoon to portion out the dough. Roll each piece into a ball.
Roll each ball in powdered sugar until well coated, then place them on the prepared baking sheets, leaving space between each cookie.
Bake in the preheated oven for 10-12 minutes, or until the edges are set but the centers are still soft.
Remove from the oven and allow the cookies to cool on the baking sheet for a few minutes before transferring them to a cooling rack.