Preheat the oven to 200°C, gas mark 6. Place the apples, blackberries, caster sugar and 1 tbsp water in a saucepan, cover and cook gently for
5 minutes until just tender. Transfer to a 1.5 litre ovenproof serving dish.
Meanwhile, rub together the butter, flour and muscovado sugar in a large bowl to resemble coarse breadcrumbs. Stir in the granola and sprinkle this over the fruit. Bake for 20-25 minutes until golden then serve.
