Preheat your oven to 350°F and lightly spray ramekins or a square baking dish with cooking spray.
Cut the bread into small cubes and peel, core, and dice the apple into bite-sized pieces.
In a large mixing bowl, whisk together the eggs, 3/4 cup almond milk, vanilla extract, cinnamon, and sugar until fully combined.
Add the cubed bread to the bowl and gently toss to ensure each piece is thoroughly soaked in the custard mixture. Let it sit for 2–3 minutes.
Gently fold in the diced apples, making sure they’re evenly distributed.
Transfer the mixture to the prepared ramekins or baking dish, spreading it out in an even layer.
Bake for 35 minutes if using ramekins, or 45 minutes in a larger baking dish, until the top is golden brown and the custard is set.
In a small bowl, whisk together powdered sugar with 1 tablespoon of almond milk to create a simple glaze. Drizzle about 1/2 teaspoon of the glaze over each serving before serving.