Arrange 1/2 of the bread cubes in a greased 9 x 13 pan. Sprinkle cream cheese cubes and blueberries evenly over the bread cubes. Top with remaining bread cubes.
Whisk together eggs, milk, and maple syrup. Pour over bread cubes and cover pan with foil. Let chill in refrigerator overnight.
Bake covered with foil at 350 degrees for 30 minutes. Remove the foil and bake for another 30 minutes or until fluffy and golden. Top with blueberry syrup.
Syrup: In a large saucepan, cook water, sugar, and cornstarch until thickened, stirring frequently. Stir in blueberries and simmer for 10 minutes. Add butter and stir until melted. Serve over the French toast.