Preheat oven to 180°C/350°F/Gas Mark 4. Combine coconut, caster sugar and flour and stir in egg whites. Mix in butter and stand for 30 minutes. Lightly grease baking trays or line with baking paper. Dollop a dessertspoonful of coconut mixture on the tray and spread out to a mango shape. Add a little more mixture if needed, but keep the wafers very thin. You will need to make 12 wafers for this dessert. Leave 3 cm (1 ¼ in) between each one. Bake for 8–10 minutes or until golden brown, then cool for 30 seconds before removing to a cake rack.