• Cooking oil spray, for greasing
• 150g frozen raspberries, thawed
• 1⁄2 cup water
• 2 Tbsp caster sugar
• 250g punnet strawberries, hulled, roughly chopped
• 1⁄2 cup self-raising flour
• 1⁄4 cup plain flour
• 1⁄4 cup cornflour
• 4 eggs, separated
• Extra 2⁄3 cup caster sugar
• 4 cups icing sugar mixture, sifted
• 20g butter, melted
• 3 cups shredded coconut
Preheat oven to 180°C. Grease a 30 x 20cm lamington tin with cooking oil spray, then line base and sides with baking paper. Put raspberries, 1⁄2 of the water and 1⁄2 of the caster sugar in a small food processor. Process until pureed. Transfer raspberry puree to a fine sieve set over a bowl. Stir puree to pass through sieve. Discard seeds. (You will need 1⁄2 cup raspberry puree.)
Rinse processor, then add strawberries with remaining water and caster sugar and process until pureed. Transfer strawberry puree to a fine sieve set over a bowl. Stir puree to pass through sieve. Discard seeds. (You will need 1⁄2 cup strawberry puree.)
Sift flours twice into a large bowl and set aside. Put eggwhites in the bowl of an electric mixer and beat until soft peaks form. Add extra caster sugar, 1 Tbsp at a time, beating well after each addition until a thick meringue mixture forms. Add egg yolks and beat until combined, then gently fold in sifted flours until well combined.
Spoon mixture into prepared tin and bake for 25-30 minutes or until mixture bounces back when lightly pressed. Allow to cool in tin for 5 minutes, then transfer to a wire rack to cool completely.
Cut cake into 24 squares. Add 1⁄2 of the icing sugar and 1⁄2 of the butter to raspberry puree and remaining icing sugar and butter to strawberry puree. Stir each until a smooth icing forms. Using 2 forks, coat 1⁄2 of the cake squares in raspberry mixture, then in 1⁄2 of the coconut. Put on a wire rack to set.
Coat remaining cake squares with strawberry mixture and remaining coconut. Put on a wire rack to set.