Preheat oven to 350F.
Oil the interior sides and bottom of an 8 inch round cake pan. Line the bottom of with parchment paper.
Sift the flour, baking powder, and cocoa powder into a mixing bowl.
Add sugar into the mixing bowl. Whisk until combined.
Add water, oil, and vanilla extract into the bowl. Whisk until combined.
Pour batter into pan. Bake for 30 minutes until an inserted toothpick comes out clean. Let cool.
Make sure to sift the flour as this is what makes the cake light and airy.
If the batter is too thick, you can add a little water until it feels right.