Heat oven to 190C/fan 170C/gas 5. Butter two 20cm sandwich tins and line with non-stick baking paper. Grate the 200g block of creamed coconut and keep half of it aside. Then in a large bowl, beat all the cake ingredients (including half of the grated block of creamed coconut) together until you have a smooth, soft batter.
Divide the mixture between the tins, smooth
the surface with a spatula or the back of a spoon, then bake for about 20 mins until golden and the cake springs back when pressed. Turn onto a cooling rack and leave to cool completely.
For the frosting, mix together the remaining creamed coconut, zest and juice of 2 limes. Microwave on High for 30 secs until the coconut melts.
Make the buttercream by beating the butter until smooth and creamy and gradually beating in icing sugar . Then beat in the cooled coconut mix and 2-3 tbsp Malibu (optional) until it becomes marshmallowy.
Fill the cooled sponges with a third of the frosting, cover the sides and top with the rest and coat the sides with the toasted desiccated coconut. Keep in an airtight container and eat within 2 days.