For rumbledethumps, first remove peel from potatoes and cut in half or quarters depending on size. Cook in half of the soup with the lid closed until soft. At the same time, cut the cabbage into eighths. Cook in the remaining soup, also with the lid closed, until soft.
Preheat the oven to 220 °C.
Peel and chop the onion and garlic. Sauté in butter until light yellow.
Grease a baking dish with butter. Alternate well drained potatoes, cabbage and onion-garlic mixture. Sprinkle with the cheese and drizzle with about 30 ml of vegetable cooking juices.
Place rumbledethumps in the heated stove and bake for about 15 minutes.