In a small bowl, mix together the cream cheese and feta with a fork.
Fill the chicken breast with the cheese mixture, spinach, and ham. (If you are using butterfly breasts, just fold over and secure with a toothpick. Otherwise make a split along one side of the breast with a knife & stuff the breast).
To Freeze: Wrap individually, label, and freeze.
To Prepare: Preheat oven to 350. Place frozen chicken breasts in a baking dish coated with non-stick cooking spray and bake, covered with foil, for one hour or until tender. You can also defrost the chicken breasts and bake them covered for 45-50 min or until tender.