Chicken and Wild Rice Casserole

I found this recipe in a Southern Living magazine. I have made a few changes due to what we like in a dish.

1 (6.2 oz) pkg fast-cooking long grain and wild rice mix
2 T butter or margarine
1/2 cup chopped green and/or red peppers and onions mixed
2 1/2 cups (about 3 small-medium) cooked, chopped chicken
2 cups shredded cheese (divided)
1 (10 3/4 oz) can cream of mushroom soup, undiluted
8 oz sour cream
1/2 cup milk
1/4 t pepper
1/4 t salt (may not be needed)

optional - 1/2 cup soft breadcrumbs and 8 oz sliced, drained water chestnuts

Prepare rice accorkding to package directions, set aside. Melt butter in large skillet over medium heat; add onions and peppers (chestnuts if used). Saute 10 min or until tender.
Stir in rice, chicken, 1 1/2 cups cheese and rest of ingredients. Spoon mixture into lightly greased 2 qt casserole. Top with bread crumbs if desired.

Bake at 350 degree for 30 minutes or until throughly hot and bubbling. Sprinkle with remaining cheese and bake 5 more minutes.