Wash the potatoes and cook them in their skins in salted water until soft. Drain, peel and slice them thickly.
Heat the butter in a frying pan, add the onions and cook slowly for 10 minutes, stirring frequently. Add the diced bacon and garlic, fry over medium heat for 3 minutes, then pour in the cream. Boil for 1 minute, transfer to a bowl and leave to cool.