200 gmdried cannellini beans, soaked overnight in plenty of water, drained (see note)800 gmDutch cream potatoes (about 5), skin on, scrubbed150 mlpouring cream80 gmbutter, coarsely chopped
Combine beans and plenty of cold water in a saucepan, simmer gently over medium heat until tender (25-30 minutes), drain and process in a food processor to a smooth paste. Return to pan and set aside.
Meanwhile, place potatoes in a large saucepan of cold salted water. Bring to the boil over medium-high heat, reduce heat to medium and simmer until tender and a skewer inserted meets no resistance (15-20 minutes). Drain and, when cool enough to handle, peel and pass through a moulis into bean purée (or mash well, then add to bean purée).
In a separate saucepan, heat cream and butter together until simmering, gradually add to potato mixture and mix until smooth. Season to taste and serve immediately with braised lamb shoulder.
Note You could substitute dried cannellini beans with 800gm
drained canned cannellini beans. Process, without cooking, in a
food processor to a smooth paste.