Preheat oven to 180 C.
Sieve the flour, baking powder, baking soda and salt 4-5 times. Keep aside.
If you want, you could powder the sugar, for easy mixing.
Take the butter in a bowl.
Add the sugars.
Beat till thick and creamy.
Add the egg, pineapple juice, coconut milk and vanilla and mix well.
Slowly add the flour mix.
Blend well, making sure no lumps remain.
Pour the batter into a prepared cake tin.
Bake for 30-35 minutes or till an inserted toothpick comes out clean.
Allow to cool completely before frosting.
This is how the cake looked after frosting and cutting.