Preheat oven to 180 degrees celsius or 350 degrees celsius
Grease a 20cmx25cm baking pan and line the base of the pan. set aside. Sift the flour and baking powder and set aside
Using an electric mixer beat the butter and sugar for 4-5 minutes until light and fluffy. Start at a low speed at first and thereafter medium speed
Add eggs, one at a time and beat until each one is well combined
Mix in the vanilla essence
Add 1/3 cup of flour/baking powder mixture and 1/3 cup milk together with the oil. Mix until combined. Repeat with the remaining flour and milk. Add the vegetable oil. Mix again until combined. Do not over mix.
Pour the batter into the lined baking pan. Tap the pan on the countertop, gently, a few times to release any air bubbles
Bake for 25-30 minutes or until a toothpick comes out clean
Allow the cake to cool in the pan for 10 minutes. Run a slim knife on the sides of the pan and gently turn the cake onto a cooling rack. Wait for it to completely cool and then decorate as desired