Preheat oven to 350 degrees. Grease a 13x9 rectangular pan. Place 8 of the bread slices in one even layer at the bottom of the pan. Set aside.
Make cream cheese filling by adding cream cheese to a bowl of a stand mixer and beat with a paddle attachment until light and fluffy, about 3 minutes. Add 1/4 cup sugar, egg, and vanilla extract. Beat until blended. Pour mixture over prepared pan with slices of bread. Spread with a spatula to create an even layer.
In a separate medium bowl, add berries and remaining 1/2 tablespoon of sugar. Toss to combine. Toss over the cream cheese filling. Top casserole with remaining 8 slices of bread and press down.
In a large bowl, add 7 eggs, ground cinnamon, vanilla extract, and salt. Whisk until eggs are beaten and mixture is combined. Add milk and half and half and whisk gently to combine. Pour mixture slowly over casserole, ensuring that it's evenly distributed. Push down with the back of a spoon to ensure bread soaks up all the egg mixture.
Bake casserole in preheated oven until fully-cooked, about 50-60 minutes. Remove from oven and let it sit for 10-20 minutes before serving.