Preheat your oven to 350°F (175°C) and grease a 9x13 inch baking pan.

In a large mixing bowl, combine the all-purpose flour, rolled oats, light brown sugar, ground cinnamon, nutmeg, and salt. Stir until well blended.

Add the cold, cubed butter to your dry mixture and cut it into the flour mixture until it resembles coarse crumbs.

Press about two-thirds of the crumb mixture firmly into the bottom of the prepared baking pan.

In a medium skillet over medium heat, combine the chopped apples, granulated sugar, apple cider, butter, cinnamon, nutmeg, and salt. Cook for about 10-15 minutes until apples soften.

In a small bowl, whisk together the cornstarch with a couple of tablespoons of water to create a slurry. Stir this mixture into the skillet and cook for another minute or two.

Pour the thickened apple filling over the pressed crust in your baking pan.

Mix the remaining crumble mixture with any leftover ingredients and sprinkle it over the apple filling.

Place the pan in the preheated oven and bake for 35-40 minutes, or until the top is golden brown and the apple filling is bubbly.

Let the bars cool completely on a wire rack before slicing into bars.