In a large bowl, add in the egg yolks, oil, and milk. Whisk together until combined.
Sift in the cake flour and corn starch. Whisk until combined then set aside.
In a separate large bowl, add in the egg whites and cream of tartar. Mix with a hand mixer until frothy then add in the sugar 1/3 at a time. Mix until you get stiff peaks
Add 1/3 of the egg whites at a time into the egg yolk batter mixture. Gently fold until combined.
Set aside a little bit of the batter in a small bowl. Transfer the remaining batter evenly into the muffin tin. This recipe makes 12 cupcakes. Gently shake the pan to even out the batter.
Add some black food coloring into the cake batter you set aside. Mix until you get a uniform batter.
Transfer the batter into a piping bag
Pipe on the desired design on top of the cupcakes
Bake at 110C/230F for 40 minutes then 160C/320F for 5-10 minutes until golden brown.
Drop the muffin pan a few times on your counter to release hot air in the cupcakes
Let cool before eating