Preheat your oven to 350°F (175°C). Peel and slice about five cups of your preferred apples and place them in a large mixing bowl. Add two cups of cranberries, half a cup of brown sugar, and a teaspoon of cinnamon. Toss to coat and set aside.

In another bowl, combine one cup of flour, one cup of rolled oats, and half a cup of brown sugar. Add a pinch of salt and another teaspoon of cinnamon. Cut in six tablespoons of cold butter until the mixture resembles coarse crumbs.

Spread the fruit mixture evenly in a 9x13 inch baking dish. Sprinkle the crisp topping generously over the fruit layer.

Bake for about 40-45 minutes until bubbly and golden brown. Let cool for 10-15 minutes before serving.

Serve warm, optionally topped with vanilla ice cream or whipped cream.