Set your oven to 160°C (320°F) with the fan function activated. Prepare two 8-inch cake pans by greasing the sides and base, and lining the bottoms with parchment paper.
Sift together the flour, cornstarch, baking powder, and salt into a mixing bowl. Whisk briefly to combine evenly.
In a separate large bowl, cream the butter, oil, and sugar using an electric mixer on medium speed for approximately 2 minutes until the mixture becomes pale and fluffy.
Incorporate the eggs one at a time, mixing thoroughly between each addition.
Pour in the vanilla extract, coconut essence, and ½ cup of the coconut milk, then mix until smooth. Set aside the mixer.
Fold in half of the sifted dry ingredients using a spatula until just blended. Add the remaining ¾ cup of coconut milk, folding gently, then incorporate the rest of the dry mixture, being cautious not to overmix.
Add the shredded coconut and fold through gently until integrated.
Divide the batter equally between the two prepared pans and bake for approximately 33 minutes, or until a skewer inserted comes out clean.
Cool the cakes in their tins for 15–20 minutes before transferring them to a wire rack to cool completely prior to frosting.