Cook the Potatoes Add peeled and chopped potatoes to a large pot. Cover with salted cold water. Bring to a boil, reduce heat, and simmer for 15–20 minutes until fork-tender. Sauté the Cabbage In a medium skillet, melt half of the butter over medium heat. Add the shredded cabbage with a pinch of salt. Sauté for 5–7 minutes until tender but not mushy. Warm the Milk In a small saucepan, heat the milk and chopped scallions over low heat for 3–4 minutes. Do not boil. Mash the Potatoes Drain the potatoes well and return them to the pot. Add remaining butter and mash until smooth. Combine Everything Stir in the warm milk and scallions, then fold in the sautéed cabbage. Season with salt and pepper to taste. Serve Hot Serve warm in bowls or on a platter, topped with an extra pat of butter.