Preheat the oven to 180°C/350°F/gas mark 4. Grease two 20cm/8 inch round cake tins and line the bases with baking parchment.
Place the flour, cornflour, desiccated coconut, bicarbonate of soda, baking powder, salt and sugar in a large bowl and stir with a balloon whisk until well combined.
Add the melted coconut oil, coconut milk, vinegar, vanilla and coconut extract (if using) and mix until well combined but be careful not to over-beat the batter or it can become tough.
Divide the batter evenly between the tins and bake for about 25 minutes until a skewer inserted into the centre comes out clean.
Leave to cool in the tins for 10 minutes then carefully turn the cakes out onto a wire rack and leave to cool completely.
To make the buttercream, melt the creamed coconut block. This can be done either in short bursts in the microwave, stirring regularly; or over a low heat in a pan on the hob. Don't let it get too hot. Set aside to cool.
Place the vegan block butter in a bowl and beat with an electric mixer until smooth. Add the sifted icing sugar and whisk until smooth and fluffy.
Whisk in the cooled creamed coconut a little at a time, whisking well after each addition. Once all of the coconut has been added you may find that the buttercream is a little bit soft. If it is then not to worry, just pop the bowl in the fridge for 15 minutes or so until it has firmed up then give it another whisk before using.
Alternatively, if you find that the buttercream is too firm, you can whisk in a little bit of coconut milk, no more than a teaspoon at a time, until it reaches the desired consistency.
Toast the coconut flakes in a pan over a low heat until golden.
To assemble the cake, place one layer on a serving platter or cake stand. Transfer the buttercream to a piping bag fitted with a large round nozzle and the coconut lime curd (if using) to a piping bag fitted with a small round nozzle.
Pipe blobs of buttercream all over the cake layer then pipe dollops of the lime curd in the gaps in between the buttercream blobs. (Or you can just spread over the buttercream and drizzle over some of the lime curd).
Place the other cake layer on top and repeat the piping of the buttercream and lime curd, Scatter over the toasted coconut and serve.