Preheat oven to 180oC. Grease two 20cm cake pans and line bases with non-stick baking paper.
Sift the combined flours and cornflour into a bowl. In a separate bowl, beat the eggs and sugar with an electric mixer for 10-12 minutes or until thick, pale and creamy. Sift half the flour mixture over the egg mixture. Use a large metal spoon to fold until just combined. Repeat with remaining flour mixture.
Divide amoung the prepared pans and smooth surfaces. Bake for 12-15 minutes or until golden and the cake springs back when lightly tapped. Set aside in the pans for 5 minutes to cool slightly before turning onto wire racks to cool completely.
To make chocolate icing, sift the icing sugar and the cocoa powder into a bowl. Stir in the water. Pour into a large shallow dish.
Spread the coconut over a large tray. Dip the base and side of one cake into the icing, allowing any excess to drip off. Place the cake, icing down, onto the coconut and turn to coat the base and sides. Transfer to a serving plate, coconut side down. Spread with jam and then with cream. Dip the top and side of the remaining cake in the icing, then in the coconut. Top the jam-covered cake with the remaining cake, coconut side up.