In a small saucepan over medium heat, bring brown sugar, butter and corn syrup to a boil, stirring constantly. Remove from heat. Pour into a greased 9x13 inch baking dish. Top with six slices of bread.
Combine sugar and 1/2 tsp. cinnamon; sprinkle half over the bread. Place remaining bread on top.
Sprinkle apple pieces evenly over bread and top with remaining cinnamon-sugar mixture. Set aside.
In a large bowl, beat eggs, milk, vanilla and 1/2 tsp. cinnamon. Pour over apples. Dot with butter.
Cover and chill 8 hours or overnight. Remove from fridge 30 minutes before baking.
Bake, uncovered, at 350 F. for 30-35 minutes.