6 (14 ounce) cans cream of mushroom soup
2 (10 ounce) cans sliced mushrooms
1 tablespoon olive oil
1 (10 ounce) package fresh bread cubes
1 cup shredded sharp Cheddar cheese
1 small onion, quartered
1 (1 ounce) square unsalted butter
1 medium white onion, quartered
5 cups shredded lettuce
Stuff the bottom of a large resealable sandwich bag with the mushrooms, oil and bread cubes. Stuff the bottom of a resealable sandwich bag with the mushrooms, olive oil, cheese, onion and lettuce. Seal and cut into 2 or 3 squares.
Heat oven to 350 degrees F (175 degrees C). Bake 20 minutes in the preheated oven.
Coat with butter, onion slices, chopped lettuce and sliced mushrooms. Slice sandwiches and set aside. Brush bread cubes with olive oil and bake 10 minutes more. Cut sandwiches into 4 pieces and place on ungreased baking sheets.
Bake sandwich squares for 10 minutes, or until golden brown. Place sandwiches in a casserole dish, place lettuce in the middle, and pour mushroom gravy over. Sprinkle with cheese and spread each with a grape jelly can.