Preheat oven to 180 degrees Celsius. Line a 20cm x 30cm lamington tray with grease-proof paper.
Sift together the flours and set aside.
Using an electric mixer, beat the eggs and sugar until fluffy and doubled in size. Gently mix through the flour, making sure it's well incorporated.
Pour the butter in slowly and fold carefully through.
Pour mixture into the prepared tin and bake for 18-20 minutes or until soft and spongy to touch. Leave to cool in tin for 10 minutes. Transfer to a cooling rack. Using a heart cookie cutter, cut sponge into heart shapes.
To make the icing, place the butter and jelly crystals in a bowl. Pour over 1/2 cup boiling water and stir to dissolve butter. Sift in icing sugar, whisk until smooth. Set aside for 1 hour to cool and thicken.
Dip each sponge heart into the icing until completely coated. Roll in desiccated coconut and serve.