Preheat oven to 325 degrees F and prepare a 9 inch round cake pan with Pam with Flour. Don't use white flour on the bottom of the pan, only the sides.
Sift the dry ingredients in a large bowl. Congratulations, you just made the the dry mix of a cake box mix.
Using a 1 cup measuring cup, mix the oil, egg, and vanilla with a fork and then mix into the dry ingredients.
Add in the water and mix until the dry ingredients are wet. Do not overbeat.
Pour into pan and bake for 30 - 35 minutes.
Let cool for 20 minutes in the pan, then invert the cake and let it cool on a wire rack.
Once cake is cool, place it in the fridge for 30 to make cutting it easier. To divide the cake into three even layers, measure the height of the cake, divide by three and mark with a toothpick. Do this in two to four places depending on if you are using a cake cutter or a serrated knife. Move the wire to line up on the top toothpicks and slice the cake. Repeat for the second layer.
Place parchment paper or waxed paper between layers, wrap in plastic on a plate and refrigerate overnight.