01 - Place the cut potatoes in a large pot and cover with cold water. Add 1 teaspoon of salt and bring to a boil. Reduce heat to a simmer and cook until the potatoes are tender, approximately 15–20 minutes.
02 - While potatoes cook, melt 3½ tablespoons of butter in a large skillet over medium heat. Add the chopped kale and sauté for 3–4 minutes until wilted and tender. Stir in the thinly sliced scallions and cook for an additional 1–2 minutes. Set the cooked greens aside.
03 - Once tender, drain the cooked potatoes thoroughly and return them to the pot. Mash them vigorously until smooth and fluffy.
04 - Gently warm the milk until it is hot but not boiling. Add the warm milk and the remaining butter to the mashed potatoes, mixing until the colcannon is creamy.
05 - Fold the sautéed kale and scallion mixture into the creamy mashed potatoes. Season with additional salt and freshly ground black pepper to your preference.
06 - Serve the colcannon hot, optionally with an extra pat of butter on top.