Preheat oven to 350°. Place chicken in a large skillet and cover with water; bring to a boil. Reduce heat; cover and simmer until a thermometer reads 165°, 12-14 minutes. Drain and cut into cubes.
In a large bowl, combine the remaining ingredients. Add chicken. Transfer to a greased 13x9-in. baking dish.
Bake, uncovered, until heated through, 45 minutes. Freeze option: Cover and freeze unbaked casserole. To use, partially thaw in refrigerator overnight. Remove from refrigerator 30 minutes before baking. Bake casserole as directed, increasing time as necessary to heat through and for a thermometer inserted in center to read 165°.