Preheat your oven to 350°F (175°C).

Cut the French bread into 1-inch cubes and place them evenly in a greased 9x13-inch baking dish.

In a large mixing bowl, whisk together the eggs, half and half, sugar, cinnamon, vanilla extract, and salt until well combined.

Pour the egg mixture generously over the bread cubes, using a spatula to gently fold and combine.

Dollop cream cheese cubes and scatter fresh blueberries over the top of the soaked bread mixture.

Cover the baking dish and refrigerate for at least 4 hours or preferably overnight.

Remove the cover and bake the casserole for 45-50 minutes until the top is golden brown.

While the casserole is baking, combine water, cornstarch, and sugar in a saucepan over medium heat; stir until thickened, then add additional blueberries.

Once the casserole has cooled slightly, slice into squares and serve warm with blueberry sauce drizzled on top.