Overnight Apple Pie French Toast Casserole

Bahan-bahan (8 porsi)

• 5 tablespoons butter
• 5 large granny smith apples (approx. 8 cups peeled and sliced)
• ⅔ cup brown sugar
• 3 tablespoons water
• 1 tablespoon cinnamon
• 1 tablespoon cornstarch
• 14 slices white bread (crusts removed)
• 6 large eggs
• 2 cups milk
• 1 ½ teaspoons vanilla extract