01 - Place the potatoes in a large pot and cover with cold salted water. Bring to a boil, reduce heat, and simmer for 15–20 minutes or until fork-tender.
02 - Meanwhile, melt 2 tbsp butter in a large skillet over medium heat. Add the chopped kale and cook for 4–5 minutes until tender and bright green. Stir in the scallions and cook for 1 minute longer. Remove from heat.
03 - Drain the potatoes well and return them to the pot. Add the milk and remaining 2 tbsp butter. Mash until smooth and creamy.
04 - Fold in the sautéed kale and scallions. Season generously with salt and pepper.
05 - Transfer the colcannon to a serving bowl and make a small well in the center. Add an extra knob of butter to melt on top before serving.