Preheat oven to 160 °C (320°F) with the fan on (see note 6 if you don't have a fan function) and line a cupcake tray with cupcake liners.
In a bowl, sift together your flour, cornflour, cocoa powder, baking soda, baking powder and salt. Using a whisk or fork, mix until well combined. Set aside.
In another bowl, add in your butter, vegetable oil and sugar. Using an electric mixer (hand or stand mixer are both fine - see note 3), cream together for 2-3 minutes until light and creamy.
Add in eggs one by one, mixing well in between each addition (about 10-15 seconds between eggs).
Add in your vanilla, vinegar and red liquid food colour, and mix until well combined. Now set your mixer aside as the remainder of the batter will be finished by hand.
Finish off by adding in half of your premixed dry ingredients to your wet mixture, and gently fold it in with a spatula until just combined. Then add in all of your buttermilk, and fold it in until just combined. Lastly, add in the remaining dry ingredients and gently fold it into the mixture until just combined. Do not overmix (see note 4).
Distribute the batter evenly into the cupcake liners (only fill about 1/2 way up), and bake for 18 minutes or until a toothpick comes out clean. Avoid overbaking the cupcakes otherwise they will dry out.
Once baked, allow them to cool in the cupcake tin for about 10-15 minutes, and then place them onto a wire rack to completely cool. In the meantime prepare the cream cheese buttercream.