I heat the oven to 375°F and grease a 9-by-13-inch baking dish.

I toss the bread cubes with olive oil and Italian seasoning, then spread them in the dish.

I warm the meatballs in the marinara, following the package directions if needed.

I spoon the meatballs and sauce over the bread, then sprinkle on both cheeses.

I cover the dish with foil and bake for 20 minutes. I uncover it and bake 10 minutes more, until the cheese melts and the edges crisp.