Preheat the oven to 350 degrees and grease a 9 x 13 inch baking dish with butter or non-stick cooking spray.
Make the topping. In a bowl, mix together the oats, flour, brown sugar, cinnamon, and salt. Add the butter and use your fingers to rub the butter into the flour until small crumbs form. You can also use a pastry cutter to do this if you prefer. Refrigerate the crumb while you make the apple filling.
Place the apples and cranberries in the prepared baking dish, then sprinkle with sugars, flour, cinnamon, ginger, nutmeg, orange zest, and orange juice. Toss well to combine then spread evenly over the pan.
Pour the crumb topping evenly over the apples and cranberries. Bake for 45-55 minutes, or until the apples are tender and the filling is bubbly. Serve warm with ice cream, if desired.