Begin by preheating your oven to 400°F and line an 8-inch square baking dish with heat-resistant parchment paper.

Core and slice the apple into twelve 1/4-inch thick pieces, leaving the skin on.

Place the apple slices in the prepared dish, drizzling melted butter over them. Ensure all slices are thoroughly coated and arranged in a single layer.

Sprinkle half of the cinnamon over the apple slices and bake them for 10 minutes.

After 10 minutes, carefully turn the apple slices and add the remaining cinnamon on top. Continue baking until the apples are golden and tender, approximately another 10 minutes.

Serve the baked apple slices warm, drizzled with the juices from the dish. Enjoy this tasty treat!