Spray 9 x 13 pan. Place one layer of bread slices in the bottom. Gently squish it together or add some half pieces to fill in big gaps. Beat cream cheese and gradually add milk, a little at a time, until it is smooth. Add eggs, half and half, vanilla, and cinnamon and beat together until combined. Ladle about half of this over the bread slices. Sprinkle on ½ of the blueberries. Add 2nd layer of bread and the rest of milk mixture. Carefully soak all the edges of the bread. Sprinkle the rest of the blueberries on top. Cover and refrigerate overnight. In morning, preheat oven to 350°. Combine butter, brown sugar, and corn syrup. Heat until bubbling. Pour over French Toast. Bake for 40 to 45 minutes.