Lightly spray a 9x13" casserole dish with non stick cooking spray. Arrange the bread slices evenly out in the baking dish, breaking up extra pieces to fill in any gaps.
1 loaf Italian bread
In a small mixing bowl, add the cream cheese, mayo, and Italian seasoning. Stir the mixture together until evenly incorporated.
4 oz cream cheese, 1/4 cup mayonnaise, 1 tsp Italian seasoning
Spoon the cheese mixture over the bread in dollops until it's all used. Use a spatula, or the back of a spoon, to spread the cheese mixture evenly out over the bread. Sprinkle the 1/2 cup of Parmesan evenly out over the top.
1/2 cup Parmesan cheese
In a separate mixing bowl, toss together the meatballs and the sauce until well coated.
1 26-32 oz bag large frozen meatballs, 1 28 oz jar pasta sauce
Spoon the the meatball mixture evenly out over the casserole, including all sauce. Sprinkle the remaining cheese evenly out over the top.
1 1/2 cups mozzarella cheese
Bake the casserole at 350 degrees for 30-35 degrees, or until golden brown & bubbly.