Put the potatoes in a medium saucepan of cold water, bring to the boil and add some cooking salt. Cook on a continuous simmer for 15 to 18 minutes, until the potatoes are tender.

Put the kale in a large saucepan of boiling salted water, bring back to the boil and cook on a continuous simmer for 6 minutes. Drain in a colander.

Meanwhile, place the spring onions and milk in a small saucepan, bring to a simmer and cook for 5 minutes.

Drain the potatoes well in a colander and let them sit for a minute or 2 to steam dry. Mash well until smooth, then stir in the hot spring onion and milk mixture. Add 25g of the butter and beat until well combined with a soft fluffy texture.

Add the potato mixture to the kale and stir until well combined. Check the seasoning, adding more, to taste, if needed. Heat through and then transfer to a serving bowl, with the other 25g of butter placed in the middle of the finished dish.