Preheat oven to 375 degrees F. Place a rack in a shallow baking pan; set aside. In a shallow bowl combine bread crumbs, cheese, and Italian seasoning. In another shallow bowl beat egg white with a fork. Dip chicken into egg white, then into crumb mixture, turning to coat. Arrange chicken in the prepared baking pan. Lightly coat tops of chicken pieces with cooking spray. Bake about 30 minutes or until chicken is no longer pink (170 degrees F) and coating is crisp. If desired, for better browning, turn the broiler on for the last 2 to 3 minutes of cooking.
Meanwhile, in an extra-large nonstick skillet heat oil over medium-high heat. Add onion; cook about 3 minutes or until tender, stirring occasionally. Add spinach, mushrooms, and garlic. Cook about 5 minutes or until spinach is wilted, mushrooms are tender, and liquid is evaporated, stirring occasionally. Remove from heat. Stir in tomatoes, basil, vinegar, salt, and pepper.
Serve chicken on top of tomato mixture. If desired, sprinkle with parsley.