||Preheat oven to 400 degrees F (200 degrees C).
||Combine bread crumbs, Parmesan cheese, salt, and black pepper in a shallow bowl; place flour into a second bowl. Whisk egg and lemon juice together in a third bowl.
||Dip each chicken breast in egg mixture and dredge in flour; dip again in egg mixture and dredge chicken in crumb mixture until coated. Place coated chicken breasts into a baking dish.
||Bake in the preheated oven until chicken is heated through and crumbs are golden, about 20 minutes.
||Spoon 2 tablespoons pizza sauce onto each chicken breast, sprinkle each with half the mozzarella cheese, and top each with half the pepperoni slices.
||Bake until chicken is no longer pink inside and the juices run clear, about 10 more minutes. An instant-read meat thermometer inserted into the thickest part of a breast should read at least 160 degrees F (70 degrees C).