Preheat the oven to 180°C and grease a rectangular baking tray (24 x 34cm).Place the butter, brown sugar and syrup in a saucepan and heat over a low temperature until the butter has melted. Add the bicarbonate of soda and stir until mixed.Mix the rolled oats, cake flour and coconut in a mixing bowl and then pour in the syrup mixture. Stir until mixed and then place the mixture in the prepared tray. Press it down evenly with the back of a spoon and bake for 15-20 minutes or until golden brown.Remove from the oven and cut into squares while the crunchies are still warm. Allow to cool in the baking tray before lifting out the squares.