Trim chicken breasts and slice in half lengthwise to create 4 cutlets. Pound to 1/3-inch thickness for even cooking. Season with salt and pepper.
Set up a dredging station: In the first bowl, mix flour, salt, and pepper. In the second, whisk eggs until frothy. In the third, combine bread crumbs and parmesan cheese.
Coat each chicken cutlet in flour (shake off excess), then dip in eggs, then press into the bread crumb-parmesan mixture for an even coating. Let the breaded chicken sit for 5 minutes.
Heat olive oil in a large non-stick skillet over medium heat. Sauté chicken in batches for 3-4 minutes per side until golden brown (it does not need to be cooked through).
Pour half the marinara sauce into a 9x13-inch casserole dish. Arrange chicken cutlets in a single layer over the sauce. Spoon remaining marinara down the center of each cutlet, then sprinkle with mozzarella cheese.
Bake uncovered at 425°F for 15 minutes, or until chicken reaches 165°F internally, cheese is melted, and sauce is bubbling.
Garnish with chopped basil or parsley if desired. Serve hot.
