01 - Place 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 - Melt 2 tbsp butter in a large skillet over medium heat. Add chopped kale and cook for 4-5 minutes until tender and bright green. Stir in scallions and cook for 1 minute longer. Remove from heat.
03 - Drain potatoes well and return to pot. Add milk and remaining 2 tbsp butter. Mash until smooth and creamy.
04 - Fold in sautéed kale and scallions. Season generously with salt and pepper.
05 - Transfer colcannon to serving bowl and make small well in center. Add extra knob of butter to melt on top before serving.