Preheat oven to 400 degrees F. Lightly coat a 15x10 in. baking pan with nonstick cooking spray; set aside.
Place each piece of chicken between two pieces of plastic wrap.
Using the flat side of a meat mallet, pound chicken lightly until about 1/2 inch thick. Remove plastic wrap. Set aside.
In a shallow dish use a fork to beat together egg white and the water. In another shallow dish combine crushed cornflakes, the 2 tablespoons grated cheese, the Italian seasoning, and 1/8 teaspoon ground black pepper.
Dip chicken pieces, one at a time, into egg mixture; dip into cornflake mixture, turning to coat. Place coated chicken in the prepared baking pan.
Bake about 18 minutes or until chicken is tender and no longer pink.
Meanwhile, cook spaghetti according to package directions; drain. In a small saucepan cook pasta sauce until heated through, stirring occasionally.
To serve, divide cooked spaghetti among four serving plates. Top with chicken and pasta sauce. If desired, sprinkle with additional cheese and/or parsley.