Preheat oven to 180 C / Gas 4. Lightly grease a medium baking tray.
Pour egg into a small shallow bowl. Place breadcrumbs in a separate shallow bowl. Dip chicken into egg, then into the breadcrumbs. Place coated chicken on the prepared baking tray and bake in the preheated oven for 40 minutes, or until no longer pink and juices run clear.
Pour 1/2 of the pasta sauce into a 20x20cm baking dish. Place chicken over sauce, and cover with remaining sauce. Sprinkle mozzarella and Parmesan cheeses on top and return to the preheated oven for 20 minutes.