Preheat oven to 400°. Spread bread cubes in a single layer in a lightly greased (with cooking spray) jelly-roll pan. Bake 12 to 15 minutes or until lightly toasted. Remove cubes from oven to a wire rack, and cool 15 minutes. Reduce oven temperature to 350°.
Whisk together eggs and next 3 ingredients in a large bowl until well blended. Whisk in milk and heavy cream until well blended.
Gently stir toasted bread cubes into egg mixture until coated. Let stand 20 minutes.
Spread bread mixture in a lightly greased (with cooking spray) 11- x 7-inch baking dish; sprinkle with Demerara sugar, if desired.
Bake at 350° for 1 hour to 1 hour and 10 minutes or until set in the center, shielding with aluminum foil after 45 minutes to prevent excessive browning if necessary. Cool 15 minutes before serving with Apple Brandy-Caramel Sauce.