Preheat the oven to 350 degrees F and lightly grease an 8-inch square baking dish.
Add the bread cubes and apple slices to the dish and gently toss them together so the apples are distributed evenly.
In a mixing bowl, whisk the eggs, milk, cinnamon, vanilla extract, and brown sugar until smooth.
Pour the egg mixture over the bread and apples, pressing down lightly so the bread absorbs the liquid.
Drizzle the melted butter over the top.
Bake for 30 to 35 minutes until the top is golden and the center is set.
Remove from the oven and let it rest for 5 minutes before slicing. Drizzle maple syrup over each serving.