Grease a 9 x 13 inch casserole. Trim off bread crusts; spread bread with mayonnaise and place on bottom of casserole. Cover with chicken, then with sliced water chestnuts. Cover entire casserole with slices of cheese. Mix well beaten eggs, milk, salt and pour over casserole. Mix together the soups and pour over casserole. Cover with foil and refrigerate overnight.
Bake at 350 degrees for 1 to 1 1/2 hours. Last 1/2 hour remove foil and cover with stuffing cubes.