Tuna Melt Casserole

12 slices bread (your favorite type)
2 cans tuna, drained
1 small onion, chopped
1/4 cup mayonnaise
6 slices cheese (your favorite type)
1 can cream of chicken soup
1/2 soup can milk

Toast the 12 slices of bread. Line the bottom of a 13 x 9-inch baking dish with 6 of the slices and set the other 6 aside.

Mix together tuna, onion and mayonnaise and spread on the bread in the baking dish. Place the slices of cheese and the remaining 6 slices of bread on top of the tuna. Finally, mix the soup and milk together and pour over the sandwiches. Bake for 20 to 25 minutes at 350 degrees F.