For the French Toast

1. Butter a 9 x 13-inch or 3-QT baking dish. Slice the bread into ¾-inch-thick slices.
2. In a large bowl, whisk together the eggs, half & half, maple syrup, bourbon, vanilla, and salt.
3. Dip each slice of challah into the custard mixture for about 5 seconds, then arrange in an overlapping pattern in the prepared baking dish. Be sure the entire bottom of the dish is covered with the bread. Pour any remaining custard over the bread. Set aside.

For the Apple Topping

1. In a large sauté pan, melt the butter over medium-high heat. Add the apples, brown sugar, maple syrup, and cinnamon. Cook, stirring frequently, until the apples are softened and the sugar-syrup is thickened, about 8 minutes. Spoon the apples and sugar-syrup evenly over the bread, making sure not to leave any of the syrup behind. If not baking immediately, cover the dish with plastic wrap and refrigerate overnight. Otherwise, proceed with the recipe.
2. Preheat the oven to 350°F and set an oven rack in the middle position.
3. Cover the baking dish with aluminum foil and bake for 25 minutes. Remove the foil and continue baking until puffed and golden, about 20 minutes more. Remove from the oven and, using a fine sieve, dust with the confectioners' sugar. Serve with maple syrup.