Preheat oven to 350 degrees F. Mix cream cheese, sour cream, 1/2 cup of the Cheddar cheese and Seasoning Mix in medium bowl until well blended. Stir in chicken.
Spoon into lightly greased pie plate. Top with remaining 1/2 cup Cheddar cheese.
Bake 20 minutes or until heated through. Sprinkle with blue cheese, if desired.