Grease 13 x 9-inch baking pan. Place half of the bread cubes evenly in prepared pan. Scatter cream cheese cubes over bread and sprinkle with 1 cup blueberries. Arrange remaining bread cubes over blueberries. In large bowl combine eggs, syrup, and milk and whisk to blend. Pour evenly over reserved bread mixture. Cover with foil and chill overnight.
Preheat oven to 350 degrees. Bake, covered with foil, in middle of oven 30 minutes. Remove foil and continue baking 30 minutes, or until puffed and golden brown.
In small saucepan combine sugar, cornstarch, and water over medium-high heat. Cook, stirring occasionally, 5 minutes or until thickened. Stir in 1 cup blueberries and simmer, stirring occasionally, 10 minutes, or until most berries burst. Add butter and stir until melted. (May be prepared up to 1 day in advance. Chill and reheat gently.) Transfer to serving bowl. Place French Toast on individual serving plates and top with Blueberry Syrup.