Spray a large baking dish (about 9-inch by 13-inch) with cooking spray. Spread half of the marinara sauce in the bottom of the dish. Add the chicken on top of the sauce. Sprinkle chicken with Italian seasoning, salt, and pepper, to taste.
Pour remaining sauce over chicken. Cover with foil and bake for 20 minutes. If you are using larger chicken breasts you will need to increase the baking time to at least 30-35 minutes.
Remove foil, place mozzarella slices and grated Parmesan on top of chicken. Return chicken to the oven (uncovered) for an additional 10 minutes, or until cheese is melted and chicken reaches an internal temperature of 165 degrees F.
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Notes
Cooking for Two? Cut the ingredients in half and bake the chicken in an 8-inch or 9-inch square baking dish.Want to prep ahead? Place all of the ingredients in the dish, cover, and refrigerate until ready to bake. You can also freeze the dish (before baking) for up to 3 months -- just make sure that it's wrapped tightly to prevent freezer burn.