Preheat the oven to 150C, 300F, Gas Mark 2.
Peel and slice the apples into a bowl of salted water. Rinse well and place in the bottom of an ovenproof dish. Scatter the blackberries over and sprinkle with 1 tbsp of the sugar.
Cut the filo pastry sheets in half to give 4 sheets. Spray a sheet lightly with oil spray and place on top of the fruit, scrunching it up to give a wrinkled effect. Repeat with the other sheets, until the fruit is covered.
Spray the top sheet lightly with oil spray, sprinkle with the remaining sugar and dust with the mixed spice.
Bake in the centre of the oven for 20 minutes until crisp and golden. Serve hot or cold with low-fat yogurt.