In a separate skillet, cook bacon and onions to desired "doneness" (I prefer well-done).
Preheat oven to 350 degrees Spread 1/3 of the mashed potatoes in 9x13 baking dish.
Top with 1/3 of the cheese followed by a layer of egg roll wrappers cut to fit. Top with bacon mixture, 1/3 of the potatoes, and 1/2 of the cheese, and more egg roll wrappers.
Spread cabbage-sauerkraut mixture over the this and top with egg roll wrappers. Spread remaining potatoes, top with egg roll wrappers, and sprinkle with remaining cheese.
Bake at 350 for 30-40 minutes or until the cheese is melted and bubbly.
Serve with Sour cream.