Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
In a bowl, whisk together the flour, cocoa powder, baking powder, and salt.
In a separate bowl, combine the granulated sugar, brown sugar, and vegetable oil.
Add the egg and vanilla extract to the sugar mixture, and mix until well combined.
Gradually add the dry ingredients to the wet mixture, stirring until just combined.
Chill the dough in the refrigerator for about 30 minutes.
Using a cookie scoop, form balls of dough and roll them in powdered sugar.
Place the dough balls on the prepared baking sheet.
Bake in the preheated oven for 10-12 minutes until the edges are set.
Allow the cookies to cool on the baking sheet for a few minutes before transferring them to a wire rack.