CALIFORNIA CHICKEN CASSEROLE

 16 ounce bag frozen California blend vegetables, thawed *
2 cups diced, cooked chicken
4 ounce can mushrooms, drained
2 stalks celery, finely chopped
1 small onion, chopped
2 tablespoons butter
1/4 cup mayonnaise
1/4 teaspoon salt, or to taste
1/2 teaspoon pepper
1/8 teaspoon garlic powder
2 ounces pimientos, diced
6 ounces Swiss cheese, shredded
Place the California blend vegetables and the chicken in a greased 9-inch square baking dish. In a medium skillet, sauté the mushrooms, celery and onion in the butter until very soft and a little browned, about 8 minutes. Stir the mayonnaise and seasonings into the vegetables until well coated. Mix in all of the remaining ingredients along with the sautéed vegetables. Cover the baking dish with foil and bake at 350º for 40 minutes. Uncover and bake 5-10 minutes longer until the casserole is browned and bubbly.