Place the potatoes in a large pot. Add 2 tablespoons salt. Cover with cold water and bring to a boil. Boil until fork tender, 15-20 minutes. Drain and return the potatoes to the hot pot. Return to the stove and cook until all of the liquid has evaporated. Mash the potatoes with a potato masher (you want them to remaining a little chunky, not completely smooth). Add the milk, 3 tablespoons butter, and salt and pepper to taste. Mash to combine. Stir in the green onions.

While the potatoes are boiling, put the cabbage in a saucepan. Cover with water, bring to a boil, and cook until tender and the cabbage turns slightly darker, 3-5 minutes. Drain the water from the pan. Add 3 tablespoons butter, cover the pan, and let sit off the heat until the potatoes are cooked and mashed.

Add the cabbage to the potatoes and stir. Place in a serving bowl and make a well in the center. Melt the remaining 2 tablespoons butter and pour into the well. Sprinkle the chives on top and serve.