Chicken chow mein casserole

I've been making this casserole since my kids were toddlers.  I think my mom gave me the recipe, but it's been so long that I can't remember. Not a figure friendly recipe, but ohhh so good!

4 - 5 cups diced cooked chicken breast
1 can condensed mushroom soup
1 can condensed chicken and rice soup
1 onion, diced
1 small can evaporated milk
1 small can mushroom pieces (including the liquid)
1 small can sliced water chestnuts(optional)
1 1/2 cups frozen green beans or peas(optional)
1 can chow mein noodles( reserve about a cup for topping)
1 tsp. black pepper
 
In a large bowl mix all ingredients together, except the reserved chow mein noodles. Pour into a 9x13 inch baking dish. Top with the reserved noodles. Bake at 350F for 30 minutes covered.  Uncover and bake for 20 to 30 minutes more.