Use cooking spray on 9x13 pan, then place bread slices into pan, slightly overlapping. Whisk together eggs, milk, vanilla, 1/2 cup sugar, 1/2 tablespoon cinnamon, and salt. Pour half of liquid mixture over bread.
Arrange apple slices over bread and pour in the remainder of egg/milk mixture. Mix the remaining sugar with remaining cinnamon and nutmeg and sprinkle over the apple slices. Slice butter and arrange on top of apples.
Cover and refrigerate overnight or at least 4 hours.
Bake at 350°F for approximately 60 minutes or until knife inserted in the middle comes out clean. Serve warm with Apple Cider Syrup.
For syrup, mix dry ingredients in a heavy saucepan. Add cider and lemon juice. Cook over medium heat, stirring until thickened.