Chocolate Lamingtons

Preheat the oven to 350u0b0F. Grease a deep 8-inch square baking pan. Line bottom with parchment paper. Line a wire rack with parchment paper.
Sift flour and cornstarch 3 times into a bowl.
Beat eggs and granulated sugar in a medium bowl with an electric mixer on high speed for 8-10 mins, until a ribbon trail forms when beaters are lifted. Gently fold in flour mixture. Pour into prepared pan. Spread lightly.
Bake for 15-18 mins, until cake springs back when lightly touched. Turn out onto prepared rack to cool.
For the ganache filling, combine ingredients in a heatproof bowl set over a pan of simmering water. Stir for 4-5 mins, until smooth. Remove bowl from heat. Cool slightly. Refrigerate for 30 mins, stirring occasionally with a wooden spoon, until thick and glossy. Using a serrated knife, slice sponge cake in half horizontally. Spread top of one cake half with ganache. Sandwich with remaining cake. Cut into 16 squares.
For the chocolate icing, place all ingredients and 2 tbsp boiling water in a large bowl. Stir until smooth.
Place coconut on a large plate. Using two forks, dip each square into icing to coat, allowing any excess to drip off. Roll in coconut to coat. Place on a wire rack. Let stand for 15 mins, until set.