Use cooking spray to grease the bottom and sides of a 9x13 pan; set aside.
Cut the bread into 1 ½ inch cubes until you have about 12 cups. Add about ⅔ of the bread cubes into the bottom of the dish.
In a small bowl, combine the cream cheese and ⅓ c sugar and stir until smooth.
Spoon the cream cheese mixture over the first layer of bread cubes. No need to spread it out - keeping it in dollops will be perfect!
Sprinkle the berries on next followed by the remainder of the bread cubes. Set aside.
In a large bowl, whisk the eggs. Then whisk in the milk, ½ c sugar and vanilla.
Pour the egg mixture into the pan. Press the bread cubes down to help each cube soak up some of the liquid. Cover the casserole with a lid or plastic wrap and refrigerate overnight.
In the morning (or when you're ready to bake it), preheat the oven to 350°F.
Bake the casserole (uncovered) for 45-50 minutes or until the internal temperature reaches 160 and the top is golden brown.
Remove from the oven and let rest a few minutes. Sprinkle with powdered sugar, if desired, and serve with maple syrup.