1 can tuna fish
1/2 c. onions, sliced
1 can cream of mushroom soup
1/3 c. milk
1/2 can water chestnuts, sliced
1 1/2 c. chow mein noodles

Mix soup and milk; add onions, chestnuts and tuna. Let stand in refrigerator for 2 hours. Place half can chow mein noodles in casserole. Top with tuna mix, then add rest of noodles. Bake at 350 degrees for 40 minutes.