Preheat oven to 425 degrees.
Peel apples, core and slice apples into quarters and slice each quarter piece into three slivers.
In a large bowl add apple slices, cranberries lemon juice, cornstarch, brown sugar, white sugar, vanilla and cinnamon. Gently toss to combine. Pour apple-cranberry mixture into 12-inch round iron skillet or 2-quart baking dish and set aside.
In a medium mixing bowl, combine yellow cake mix, brown sugar, salt and baking powder. Stir to combine. Add butter, and using a pastry blender or a fork, cut butter into the mixture until it resembles coarse crumbs.
Add crumb topping to evenly cover the apple-cranberry mixture. Set in the oven and bake for 35-45 minutes or until crumb topping is a nice golden brown and the juice from the apples and cranberries is bubbling.
Serve immediately or let it cool and serve later, it's great either way especially with vanilla ice cream or homemade whipped topping.