Preheat your oven to 375°F (190°C). Grease your baking dish lightly to prevent sticking.
Arrange the sliced apples evenly across the bottom of the dish. Sprinkle with ground cinnamon, salt, and pepper for flavor.
Scatter the cooked chicken over the apples, creating an even layer that will serve as the hearty base of the casserole.
Sprinkle the shredded cheese evenly across the chicken layer, ensuring good coverage for melty richness.
Combine the bread crumbs with melted butter to create a buttery crumb topping, then sprinkle this mixture evenly over the entire casserole.
Place the dish in the oven and bake uncovered for about 35-40 minutes, until the topping is golden brown and bubbling around the edges.
Remove the casserole from the oven and let it rest for a few minutes; the topping will crisp further as it cools slightly, and flavors will meld beautifully.
Slice and serve hot, enjoying the combination of tender chicken, sweet apples, and crunchy topping in each bite.