1. Preheat the oven to 350°F (175°C) and grease a 9×9 inch baking dish.

2. In a bowl, toss apples and cranberries with granulated sugar, lemon juice, cinnamon, nutmeg, and 1 tablespoon flour until evenly coated.

3. In a separate bowl, combine oats, 3/4 cup flour, brown sugar, and salt, then cut in cold butter with a pastry cutter until mixture forms coarse crumbs and fold in nuts if using.

4. Spread the fruit mixture evenly in the prepared dish and sprinkle the oat topping over the fruit in a uniform layer.

5. Bake uncovered for 40 to 45 minutes until the filling is bubbling and the topping turns golden brown.

6. Let the crisp cool for 10 to 15 minutes before serving to allow the juices to thicken and the topping to set.