Preheat the oven to 350°F (175°C).
In a large bowl, combine the cubed bread and chopped apples.
In another bowl, whisk together the eggs, milk, brown sugar, cinnamon, and salt until well combined.
Pour the custard mixture over the bread and apples, gently folding to combine.
Stir in the shredded BBQ chicken and nuts (if using).
Transfer the mixture to a greased baking dish, spreading it out evenly.
Bake in the preheated oven for 45-50 minutes, or until set and golden brown on top.
Allow it to cool slightly before serving.