Preheat oven to 350 F. Lightly grease an 8x11-inch baking dish (or 7x11).
In a large bowl, toss apples, cranberries, sugar, flour, and orange zest together.
3 cups peeled and sliced tart baking apples, 2 cups fresh cranberries¹, 1 cup sugar, 3 tablespoons all-purpose flour, 1 tablespoon fresh orange zest
Pour into a prepared baking dish. Set aside.
In a medium bowl, mix topping ingredients until crumbly; sprinkle over apple mixture. You can press crumbles together and drop over apples or just sprinkle.
2 cups old-fashioned oats, ½ cup all-purpose flour, ½ cup brown sugar, ½ cup butter
Bake for 45-55 minutes, or until fruit is bubbly and topping is lightly browned.
Notes
You can substitute an equal amount of frozen cranberries.