Preheat your oven to 350°F (175°C). Grease and line the baking pan with parchment paper for easy removal.
In a large mixing bowl, whisk together the granulated sugar, brown sugar, and vegetable oil until well combined.
Add the eggs one at a time, mixing well after each addition. Stir in the vanilla extract.
In another bowl, whisk together the flour, cocoa powder, baking powder, and salt until fully combined.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined. Do not overmix; a few lumps are fine.
Pour the batter into the prepared baking pan, spreading it evenly.
Bake in the preheated oven for 25-30 minutes or until a toothpick inserted in the center comes out with a few moist crumbs.
Allow the cake to cool in the pan for about 10 minutes. Then, lift it out using the parchment paper and let it cool completely on a cooling rack.
Once cooled, dust the top with powdered sugar, creating a crinkled appearance with a sweet finish.
Cut into squares and serve.