Boil 5 quarts of water in a large pot. Add 2 teaspoons salt and spaghetti. Cook about 10 min. or until tender. Drain. Set aside.
Save ½ cup pasta water plus extra if needed. Wipe off the chicken with a wet paper towel. Using the palm of your hand, flatten the chicken to even thickness or use a mallet and put chicken between 2 pieces of plastic to flatten to about ½ inch thick.
Beat the egg in a shallow dish. In a food processor or blender process the bread until crumbs. Place in a shallow dish and stir in the Italian seasoning.
Dip chicken into egg, then in crumbs to coat.
In a large fry pan over medium heat, melt the butter. Brown the chicken on both sides.
Add the spaghetti sauce and ½ cup pasta water. Reduce the heat to low; cover and simmer for 10 min. Sprinkle both cheeses on top.
Cover and simmer again for 5 min. or until the cheese melts. If sauce is too thick, add more pasta water.
Serve over drained hot spaghetti.