Preheat the oven to 200°C/400°F/gas mark 6. Finely chop the nuts and put them into a small mixing bowl with the sugar. Stir to combine.
Quarter and core the apples, then thinly slice them about 3mm thick. Put the slices into a mixing bowl with the maple syrup, 1 teaspoon of orange zest and 3 tablespoons of juice, and the cinnamon. Toss so that the apple slices are evenly coated.
Place a sheet of filo pastry on a large baking tray and brush lightly with olive oil. Place another 2 sheets of filo on top, brushing each sheet with olive oil. Then sprinkle over two-thirds of the nut mixture. Place another 3 sheets of filo on top of the nuts, brushing the sheets with oil as you go.
Arrange the slices of apple on the final sheet of filo, leaving around 2ócm clear on all sides. Save the leftover syrup in the bowl for later. Sprinkle the remaining nut mixture on top, then fold the edges of the filo up over the apples and brush with olive oil. Bake for 25–30 minutes, or until the filo is golden brown and the apples are cooked.
Remove the tart from the oven, pour the reserved syrup all over, and serve with scoops of ice cream.
Tip: Simply refrigerate or freeze any leftover filo pastry in an airtight container to save it for another day.