Mix egg and milk in a shallow dish.
Mix bread crumbs and parmesan cheese in a seperate shallow dish.
I like to cut my chicken in half, then take a meat tenderizer to them. Then coat chicken in egg mixture followed by bread crumb mixture. Fry in olive oil 5 minutes on each side.
Pour 1/2 jar of sauce in a 8x8 pan, lay chicken on top, adding 2 spoonfuls of sauce on top of chicken, then top with mozzarela slices. Cover with foil, bake at 325 for 25 minutes. Then add remaining sauce around chicken if you want more sauce, broil until cheese is melted and toasty.