Combine first 3 ingredients in a saucepan. Bring to a boil; cover, reduce heat, and simmer 45 minutes or until giblets are fork-tender. Drain, reserving broth.
Remove meat from neck; coarsely chop neck meat and giblets; set aside.
Add water to reserved broth to equal 3 cups. combine broth, chopped neck meat, giblets and next 7 ingredients. Bring to a boil; reduce heat, and simmer, uncovered, 30 to 45 minutes.
Combine cornstarch and 1/4 cup water; stir into broth mixture. Bring to a boil; boil 1 minute.
Serve gravy hot over turkey and dressing.Makes 2 2/3 cups