Pre-heat the oven to 175°C.
Melt the butter in a medium-sized skillet and then add the apples, brown sugar and cinnamon.
Cook until the sugar has melted and the apples are soft. Stir in the blackberries and remove from the heat.
Melt the butter and set to one side.
In a large bowl, mix the oats, macadamia, cinnamon, flour and sugar. Add the butter and stir until combined.
Pour over the apple and blackberry mixture and press down with the back of a spoon until it is even.
Bake for around 30 minutes until the top is golden brown and the fruit is bubbling up. Leave to cool a little then serve with vanilla ice-cream. Enjoy!