Place the potatoes into a medium pot of lightly salted water. Bring to a boil, then simmer for 15-20 minutes until the potatoes are fork tender, but not falling apart. Drain and place into a large bowl along with the cream and butter. Keep warm.
While the potatoes are boiling, place the butter and onions into a medium sized frying pan. Fry until the onions are soft. Add in the cabbage and fry until softened to your liking. (some people prefer a toothsome cabbage; some prefer it quite soft.)
At this point, the potatoes should still be hot as you have been cooking the cabbage while the potatoes boiled. Mash the potatoes/butter/cream until smooth.
Stir in the hot cabbage, green onions, half of the bacon and salt and pepper to taste.
Place in a bowl and garnish with the remaining bacon and the fresh parsley.
Feel free to adjust the ratios, you can use more cabbage and less potatoes, more bacon ,etc.