Cut bread into 1 inch cubes; place half is a greased 13x9x2 baking dish. Cut cream cheese into 1 inch cubes; place over bread. Top with blackberries and remaining bread. In a large bowl, beat eggs. Add milk, cinnamon, and syrup; mix well. Pour over bread mixture. Cover and chill 8 hours or overnight.

Remove from refrigerator 30 minutes before baking. Cover and bake at 350 degrees for 30 minutes. Uncover; bake 25-30 minutes more, or until golden brown and the center is set.

For blackberry sauce: In a saucepan, combine sugar and corn starch; add water. Bring to a boil over medium heat; boil for 3 minutes, stirring constantly. Stir in blackberries; reduce heat. Simmer for 8-10 minutes or until berries burst. Stir in butter until melted. Serve over french toast. Yield: 6-8 servings (1 3/4 cups of sauce).