You will need a rimmed baking sheet; a large pot or saucepan, 6-quart capacity; a 3-quart baking dish or oval gratin dish; heavy aluminum foil. Arrange a rack in the middle of the oven, and heat it to 400º. Trim the crusts from the bread slices, lay them flat on the baking sheet, and put it in the oven as it heats. Toast the slices, turning them over once, until lightly browned on the edges. Remove and let cool, leaving the oven on.  Meanwhile, bring 4 or 5 quarts lightly salted water to the boil in the big pot. Slice the cabbage head in half, and cut out the core completely, so the leaves can separate. Discard all tough and torn outer leaves, lay the cabbage halves cut side down, and slice crosswise into 1-inch strips. Drop the cabbage strips into the water, return to the boil, and cook until tender, 10 to 15 minutes. Pour the strips in a colander, rinse under cool water, and let drain. Put them in a bowl, sprinkle them with the salt and olive oil, and toss well.  Slice the chunk of provolone into slabs, about ⅓ inch thick. Butter the sides and bottom of the baking dish. To assemble the casserole: Cover the bottom of the baking dish with a layer of bread slices, trimming the pieces as needed to fit snugly and fill any gaps. Spread half of the seasoned cabbage strips in a layer over the bread. Lay all of the provolone slabs on top of the cabbage, evenly distributed in a single layer. Sprinkle on half of the grated cheese. Next, spread the remaining cabbage out in an even layer, and top that with the remaining bread in another snugly fitted layer. If the final layer of the bread rises over the baking dish, press down gently with your palm to compress the layers a bit, making room for the stock. Slowly pour the stock all over the bread and down the insides of the pan, so everything is moistened. Sprinkle the rest of the grated cheese over the top. Carefully tent the dish with a sheet of heavy aluminum foil, arching it so it doesn’t touch the food surface, and pressing it against the sides. Set the dish on the baking sheet, and place in the oven. Bake the casserole for about 45 minutes, until the juices are bubbling actively, and remove the foil. Continue baking for 20 minutes or more, until the top of the casserole is golden brown all over.

Serve the soup steaming hot. Set the baking dish on a trivet, cut portions with a knife, and lift them out with a wide spatula or serving spoon into warm shallow bowls. Scoop up any remaining liquid with a spoon and pour it over the portions.