1. In a small pan melt butter and sugar together. Whisk to combine. Cook until slightly thickened. Add bourbon and whisk again. Continue to cook for about 1 minute.
2. Pour butter mixture into a 9″ x13″ pan. Arrange sliced apples on top.
3. Arrange slices of bread on top of apples.
4. In a large bowl, beat together eggs, milk, vanilla, cinnamon, and nutmeg. Pour mixture over bread.
5. Cover dish and refrigerate overnight (see note below). In the morning, place casserole dish in the oven. Heat to 350ºF. Bake for 45 minutes to 1 hour, or until apple slices have softened and bread is golden brown.

Note: If you are preparing the casserole the morning you are serving it, dip bread slices in egg mixture before putting them in the pan. Pour remaining egg mixture over the top of bread slices. Bake at 350ºF for 40-45 minutes.