1. Preheat the oven to 180°C/350°F/gas mark 6. Scatter the apple and figs in an even layer over the base of a 2.6 litre rectangular Pyrex dish and sprinkle with the sugar and orange zest.
2. Combine the cold butter, flour and salt in a food processor and pulse until the mixture resembles breadcrumbs. Tip into a large Pyrex bowl and gently mix with the porridge oats and demerara sugar. Sprinkle the mixture in an even layer over the fruit.
3. Bake in the preheated oven for 30 minutes until golden brown on top. Remove from the oven and leave to cool slightly before serving.
4. Serve with custard, cream or ice cream.