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 until tender.
02 - Bring a separate pot of salted water to a boil. Add sliced kale and blanch for 2–3 minutes until wilted. Drain well and set aside.
03 - In a small saucepan, heat milk with half of butter until just warm. Add spring onions and let infuse for 2 minutes on low heat.
04 - Drain potatoes and return to pot. Mash until smooth and lump-free.
05 - Stir in warm milk with spring onions and remaining butter. Mix until creamy. Fold in blanched kale. Season generously with salt and pepper.
06 - Serve hot, with an extra knob of butter melting in the center of each serving.