Preheat oven to 350°F (177°C). Line an 8 x 8 inch baking pan with parchment paper.
In a large mixing bowl, add flour, baking powder, salt and sugar. Whisk until evenly combined. Then do a quick sift of your mixture by running your whisk rapidly back and forth through the flour until it looks light and powdery. This is an important step because it makes it much easier to mix your batter and not overwork it.
Add in vanilla, oil and half of the water. Do not add the entire amount of water, otherwise you won't be able to mix out the flour lumps. Whisk until your batter is smooth and no flour lumps remain. Your batter will be very thick. Once batter is smooth, add in remaining water and whisk again until batter is smooth.
Pour batter into prepared baking pan. Bake for about 38 minutes or until cake is very lightly browned on top and toothpick inserted comes out clean. (I found it's better to bake this cake a little longer than just the toothpick coming out clean in order have a better flavor. The cake is done for me at 35 minutes using the toothpick test but I bake a little longer until the top is just starting to brown. Let the cake cool completely in pan before removing and cutting. If adding frosting, add it after the cake has cooled.
Notes
If you have self-rising flour, this cake can also be made with self-rising flour. Simply use 1 3/4 cups (230 g) of self-rising flour and do not add baking powder and salt into the cake (since it's already in the self-rising flour).
This cake can also be baked in an 8 inch round cake pan.
If you have butter, you can use melted butter instead of oil. I think butter gives the cake a slightly better texture and flavor but the oil version is still pretty good.
Optional Buttercream Frosting: I added buttercream frosting on top. For the frosting, you will need 1/4 cup unsalted butter (softened to room temperature), 1 cup powdered sugar, 1/2 tsp vanilla extract, and 1.5 tbsp of milk. Cream butter until light and fluffy. Gradually add in the sugar and continue beating until sugar is fully incorporated. Add in the vanilla and milk and beat again on high speed for about 3 minutes or until frosting increases in volume and becomes very light and silky. You can add more milk if needed to reach desired consistency.
The nutrition information provided are only estimates based on an online nutritional calculator. This is not a comprehensive list of all the nutrients in the recipe (i.e., does not include vitamins, cholesterol, etc). I am not a certified nutritionist. Please consult a nutritionist or doctor for accurate information and any dietary restrictions and concerns you may have.