In medium saucepan, over medium heat, bring brown sugar, butter, and corn syrup to a boil, stirring constantly. Add apples, reduce heat, and cook just until sauce begins to thicken, about 3 to 5 minutes. Pour into greased 9x13-inch pan.
In separate 9x13-inch pan place French bread slices on bottom.
Pour mixture over bread. Cover and refrigerate both pans overnight.
In the morning: Remove from refrigerator 30 minutes before baking. Place bread slices over caramel-apple mixture. Spread 2 to 3 tablespoons butter over bread slices. Bake in pre-heated 375 degrees F oven for 35 to 40 minutes or until knife inserted into center comes out clean.