Combine the buttermilk and seasonings in a large zip-style freezer bag. Mix together by using your fingers on the outside of the bag.
Pound the chicken thin. Working with one chicken breast at a time, place inside a gallon zip-style freezer bag and pound with a rolling pin to an even ½-inch thickness.
Set the flattened chicken breast into the seasoned buttermilk. Shake the bag slightly to fully emerge the chicken breast in the buttermilk mixture. Repeat with the remaining breasts. Refrigerate a minimum of 4 hours and up to 24 hours.
Line a half sheet pan with heavy-duty aluminum foil and spray with cooking spray, set aside. Or butter a 9x13-inch baking dish, set aside. Preheat the oven to 375 degrees F.
Mix the seasoned bread crumbs and parmesan cheese together in a shallow baking dish or large zip-style bag.
Using tongs, shake the excess buttermilk off the chicken breasts and coat with breading. Dip each chicken breast into the bread crumb mixture, one at a time. Press the bread crumbs to the chicken so each breast is fully coated.
Place each coated piece of chicken on the prepared half sheet pan or in buttered baking dish. Cover the entire pan with aluminum foil. Bake in the preheated oven for 30 minutes.
Remove the aluminum foil, drizzle with zesty Italian dressing and continue to bake for 20-30 minutes. Or until the internal temperature of the chicken reaches 165 degrees F.
Let the chicken breasts cool 5 minutes before slicing.