
When there’s no space on the stovetop to boil and mash potatoes, braise and mash them in a slow cooker — an easy and forgiving one-pot method. This rustic version has big flavors, thanks to the garlic that's cooked and smashed with the potatoes. The five garlic cloves lends a fairly assertive flavor, so decrease it to 2 or 3 cloves if you want a more subtle effect. You can leave the dish on warm for up to 3 hours after you mash the potatoes, just stir in the Parmesan and parsley right before serving.
Toss together the potatoes, garlic, olive oil, juice of 1/4 the lemon (about 1 tablespoon), salt and a generous amount of black pepper in a 5- to 8-quart slow cooker. Cover and cook on high, stirring once or twice to encourage even cooking, until the potatoes are very tender, about 4 hours.
Coarsely mash the potatoes and garlic with a potato masher. Just before serving, fold in the Parmesan, parsley and remaining 1 tablespoon lemon juice. Taste for seasoning and add more salt and pepper if necessary.