You will need to increase cooking time by 15 minutes if you assemble it and refrigerate it overnight. I also only made a ½ batch for our family in an 8x8 square pan.
1 (16oz) loaf French bread, cut into 1 1/2” slices
3 cups milk
3/4 cup sugar, divided
1T vanilla extract
5 (or so) granny Smith apples, peeled, cored, and sliced
2 tsp ground cinnamon
3T butter, cut into pieces
Arrange the bread slices in a single layer in a greased 9×11 baking dish. In a mixing bowl whisk together the eggs, milk, 1/4 cup of the sugar, and the vanilla. Pour half of the mixture over the bread. Next arrange the apple slices over the bread. Pour the remaining egg mixture over the apples. Mix together the ½ cup sugar with the cinnamon and sprinkle over apples. Dot the top with butter. Bake at 400 for 30 minutes. Let stand for 10 minutes before cutting and serving.