The slow cooker takes an already-simple classic recipe and makes it even easier. Simply toss cut russet potatoes, butter and a touch of salt and pepper into a slow cooker, turn it on low and walk away for a few hours. When you return, the potatoes will be perfectly tender and ready to be mashed. Best of all, the slow cooker traps all the potato flavor, making these spuds extra potatoey.
Toss the potatoes, butter, 1 tablespoon salt and 1/2 teaspoon pepper together in a 6-quart slow cooker. Add 1 cup of water, then cover and cook on high until the potatoes are tender, about 4 hours. (The potatoes might have browned lightly in spots but that is okay.)
Remove the lid and add the sour cream and 1 1/2 cups warm milk to the potatoes. Use a potato masher to smash the potatoes until they are mostly smooth. If the potatoes need to be thinned out, stir in the remaining 1/2 cup warm milk. Season to taste with additional salt and pepper. Garnish with chives.