In the bottom of a mixing bowl, use a wooden spoon/potato masher/fork to roughly mash the remaining 1 cup of berries. Add in the sugar and eggs, whisk together. Pour in the milk, vanilla and spices, whisk again.
The night before,spray a 9×13 baking pan with nonstick cooking spray. Add the bread cubes and 2 cups of the blueberries, toss together, and set aside.