Preheat the oven to 360 degrees F and line an 8-inch or 9-inch springform pan or cake pan with parchment paper.

Add the flour, sugar, cocoa powder and baking powder to a mixing bowl and stir well using a whisk until any clumps are out.

In a separate bowl or measuring cup, combine the water, oil and vanilla extract.

Pour the liquid into the bowl with the dry ingredients and stir everything together until combined. The batter will be very thick - this is normal!

Transfer the batter to the prepared cake pan and smooth into an even layer.

Bake on the center rack of the preheated oven 30 to 35 minutes, until the cake has risen substantially and has a nice firm crust on top.

Allow cake to cool at least 20 minutes before releasing it from the mold. Sprinkle with powdered sugar, leave plain, or frost it with frosting of choice.