Preheat the oven to 375°F.
Crack the eggs into a large bowl. Add cinnamon and whisk well.
Add milk and vanilla extract, and stir until everything is well combined.
Sieve the egg mixture into a large bowl of bread chunks. Gently give it a toss to coat them evenly in the egg mixture. Cover and refrigerate for at least 15 minutes.
Soak raisins in 1/4 cup of warm water.
Melt butter over low heat. Add apples, sugar, and cinnamon, and cook for 10 minutes. Add soaked raisins and raisin water, and cook for another 2 minutes. Remove the pan from the heat.
Toss the soaked bread with the room-temp cooked apple and nuts. Pour the mixture into a large baking dish, foil, and bake for 45 minutes.
When it’s done, take it out of the oven. Add confectioner’s sugar to a sieve and gently dust all over the surface of the casserole.
Divide the casserole into four with a knife and carefully lift each piece out. Place onto serving plates and drizzle with maple syrup to serve.