• Preheat your oven to 165 °C (330 °F) fan (or 180 °C/350 °F conventional). Grease and line two 8‑inch cake tins.
• In a bowl, sift together the flour, cornstarch, baking soda, baking powder, and salt. Whisk to combine and set aside.
• In a mixing bowl (or stand mixer), beat the room‑temperature butter, oil, and sugar on medium speed for about 2 minutes until light and creamy.

  An electric hand mixer like this makes the job much quicker and easier.
• Add the eggs one at a time, mixing just until each is incorporated (about 10–15 seconds each).
• Stir in the vanilla extract and white vinegar.
• Pour in ½ cup of buttermilk and mix until just combined.
• With a spatula, gently fold in half of the dry ingredients until you no longer see streaks of flour.
• Add another 1 cup buttermilk, fold again until just combined.
• Finish by folding in the remaining dry ingredients, take care not to over mix.
• Grease and line your cake tins. These non-stick tins help the cakes release cleanly every time. Divide the batter evenly between your prepared tins.
• Bake for 30 minutes, or until a toothpick inserted into the centers comes out clean.
• Let them rest in the tins for 15–20 minutes, then turn out the cakes and cool completely on a cooling rack like this, before frosting.

Vanilla Buttercream Frosting

• In your mixer bowl, combine the softened butter, powdered sugar, vanilla extract, and milk or cream.
• Start mixing on low speed until the sugar and butter come together (about 1 minute).
• Increase to medium‑high and whip for 10 minutes, scraping down the sides halfway through, until the frosting is light, fluffy, and spreadable.
• Place one cake layer on your serving plate, spread a thick layer of buttercream on top, then set the second layer over it. Frost the top and sides as desired, then slice and enjoy!