Champ should be soft in consistency but not sloppy. Once mastered, this recipe can be adapted for different results. Try replacing the milk with crème fraiche or quark (skimmed-milk soft cheese), or add some steamed cabbage to turn it into that other Irish favourite, colcannon.
Cover the potatoes with cold water in a pan and add a pinch of salt. Bring to the boil, then simmer for 15-20 minutes or until completely tender when pierced with the tip of a sharp knife.
Heat the milk in a pan with the spring onions for 5 minutes until the spring onions have softened. Drain the potatoes in a colander and then peel while they are still hot. Push through a potato ricer or sieve using a spatula. Beat 40 g/1 1/2oz of the butter into the warm mashed potato and then mix in the milk and spring onion mixture. Season to taste.
To serve, spoon into a warmed serving dish and make a slight dip in the middle. Add the remaining knob of butter and allow it to melt into the champ.