Loch Lomond Rumbledethumps - cooking recipe

Ingredients

6 cups yukon gold potatoes (cut into large chunks. Do NOT peel!)
6 cups savoy cabbage (shredded very thin)
1/2 cup water
1 large yellow onion (diced very small)
8 tablespoons butter (divided in half)
1/2 cup milk, hot
8 ounces sharp cheddar cheese (shredded and divided in half)
3 -4 medium tomatoes (sliced thinly)
kosher salt & fresh ground pepper

Preparation

Preheat oven to 400 degrees. Grease a 9\" x 13\" pan. Set aside.
Cut very thin slices from a head of well-washed Savoy cabbage, totaling 6 cups.
Chop one large Spanish onion into small pieces.
Place 4 tablespoons of butter in a large Texas skillet. Heat until butter melts and add chopped onions. Cook onions for 5 minutes over medium heat. Slowly add 1/2 cup of water and add the finely chopped cabbage. Season with Kosher Salt and Freshly Ground Black Pepper to taste. Stir mixture together and cover tightly with lid.
Every 5 minutes or so, lift the lid and stir the onion/cabbage mixture until the cabbage has shrunk, become tender and begins to brown very, very lightly. (The reason why the cabbage is sauteed rather than boiled is to increase it's natural sweetness and deepen the flavour). It will take 30 to 45 minutes for the cabbage to wilt and cook thoroughly.
While cabbage and onions are cooking, cut Yukon Gold potatoes into large chunks, about 6 pieces per potato. You do NOT want to dice them as this will cause your potatoes to become waterlogged. Place potatoes in a large pot of cold water and bring to boil. Check tenderness of potatoes every 5 minutes and when \"fork tender\" drain off water.
Place cooked potatoes in a very large bowl with 4 tablespoons of butter, 1/2 cup of hot milk, and enough Kosher Salt and Freshly Ground Black Pepper to taste. Mash potatoes, DO NOT WHIP! The potatoes should not be \"wall paper paste smooth\" but slightly chunky. If potatoes are done before cabbage mixture, cover to keep warm.
Check cabbage/onion mixture. If more water is needed to steam the cabbage, add only 1/4 cup additional. When cabbage is done, if there is remaining liquid, take lid off of pan and cook the extra water \"off'.
Add cabbage/onion mixture to the mashed potatoes, stirring until well combined.
Place the mixture in the greased 9\" x 13\" pan.
Thinly slice the tomatoes, about 1/4\" thick. She used 2\" diameter tomatoes so that each slice of the dish had a tomato on top.
Sprinkle 2 cups of the finely shredded Sharp Chedar cheese on top of the potato/cabbage mixture. Top with tomato slices. Very lightly salt and pepper each slice of tomato. Add remaining 2 cups of cheese over the tomatoes and potato mixture.
Place casserole dish in 400 degree oven for 30 minutes or until the cheese is completely melted, potatoes are bubbling and tomatoes are thoroughly cooked.
Remove to heat-proof surface and allow to sit at least 5 minutes before serving. This stays VERY HOT for a long time! Be careful to not burn your mouth, like I did! LOL.