Preheat the oven to 325°F. Grease an 8-inch square baking dish or 6 5-ounce ramekins.
For topping, combine flour, oats, sugar, cinnamon, salt and butter in a bowl. Work together with fingertips until crumbly. Stir in nuts and set aside.
Toss the apples and cranberries with sugar, orange zest and juice. Spoon into prepared baking dish(es). Sprinkle topping evenly over the fruit. Bake until bubbly and apples are tender, about 30 minutes. Let cool slightly. Serve warm, topped with ice cream or cream, if desired.