Grease a 9" x 13" baking dish with butter. Remove the ends from the bread loaves and cut loaves in half lengthwise.
In a mixing bowl, blend 1 cup blueberries and cream cheese.
Spread the cream cheese mixture on both sides of the bread and put halves together to form a sandwich.
Cut loaves into 1" cubes and toss into baking dish.
In a large mixing bowl whisk together eggs, maple syrup, cream, vanilla, and cinnamon.
Pour egg mixture over the cubes.
Press bread down gently to flatten. Sprinkle remaining blueberries over top.
Cover and refrigerate overnight.
Preheat oven to 350°.
In the morning, bake at 350° for 55-60 minutes or until puffy and golden. Serve with maple syrup.