Preheat your oven to 180 degrees. Use 1 tablespoon of the melted butter to grease two x 20cm round cake tins and then sprinkle 2 teaspoons of cornflour over each greased tin. Give the tins a good shake to evenly coat the cornflour before tipping out the excess. Line the base of each tin with a sheet of baking paper.
Use an electric mixer to beat together the eggs, caster sugar and vanilla extract for approximately 8 minutes or until it becomes thick and creamy.
In a small bowl, sift together the self raising flour and remaining 1 tablespoon of cornflour three times.
Sift the flours over the egg mixture, and using a large metal spoon, gently fold the ingredients together.
Combine the remaining 1 tablespoon of melted butter with the boiling water in a small jug and pour down the side of the bowl into the egg mixture. Fold until just combined.
Divide the mixture evenly between the two cake tins and place in the oven to bake for 20 minutes, or until the sponges are golden and a skewer inserted into the centre of the tin comes out clean. Allow the cakes to cool in their tins for 5 minutes before carefully turning onto a wire rack to completely cool.
Once the cakes have cooled (ideally waiting until the next day), it's time to make the chocolate icing. Place the coconut in a large container and set aside until needed.
Combine the cocoa, icing sugar and water in a large container (big enough for the cake to fit in) and mix until all the ingredients have combined. You want the icing to be quite runny, so add a little water if it's too thick.
Carefully coat each of the cakes in the chocolate icing - I find it easier to hold the cake with one hand and pour the icing over the top of it with a ¼ measuring cup. Once the cake has been completely covered with icing, place it in the container with the coconut and cover.
Repeat above to cover the second cake with icing and coconut.
Allow the icing to set on both of the cakes before carefully slicing each cake in half horizontally.
Place the thickened cream, extra icing sugar and vanilla extract in a medium sized bowl and beat with electric beaters until soft peaks form.
Place one layer of cake on your serving plate - leaving exposed cake on top. Carefully cover the surface with raspberry jam and cream. Place the next layer on top of the jam and cream and repeat.
Continue until all three layer have been covered in jam and cream before carefully placing the final layer on top of the cake.
You can sprinkle the cake with a little extra coconut if you like.