Evenly spread the olive oil into the bottom and sides of your slow cooker.
Place egg in a bowl, and beat with a fork. Set Aside. In another bowl, mix together: bread crumbs, parmesan cheese, salt, and pepper.
Dip the chicken into the egg, then into the bread crumbs mixture, coating all sides.
Place the chicken breast pieces in the bottom of the slow cooker.
Layer 1 cup of mozzarella cheese on top of chicken, and pour sauce over the cheese and chicken.
Close lid and cook on LOW for 6 hours or HIGH for 3 to 2 1/2 hours.