Scrub your potatoes clean, cut them in half, and put them into a pan of salted, boiling water. Boil for about 10 minutes until tender. Stick a knife into them to check they're soft all the way through. Drain in a colander and return them to the pan. Add the milk, butter, and a pinch of salt and pepper. Mash until smooth and creamy, adding another splash of milk if necessary. Pick a rosemary leaves off the woody stalk and lightly push them into the potato. You can drizzle with a little olive oil, or use olive oil instead of butter.
This recipe is taken from Jamie's Food Revolution by Jamie Oliver (Hyperion). © Jamie Oliver, 2009