In a medium sized mixing bowl , mix 6 large eggs , 1 cup half and half , 1 cup 2% milk , ½ cup granulated sugar , 2 teaspoons vanilla , and 1 teaspoon cinnamon together. Set aside.
Spray a 9x13 inch pan with cooking spray and place half of the 1 (16 ounce) cubed loaf challah bread in the bottom. Layer with half the 3 Granny Smith apples peeled and sliced thin and pour about a third of the egg mixture over it. Repeat again with the remaining bread, apples, and mixture. Cover with plastic wrap and place in the fridge overnight or for at least 4 hours.
Overnight Cinnamon Apple French Toast Casserole · Dinner Match Lab | Dinner Match Lab