Scrub the potatoes, peel or don’t peel. Cut into large chunks and place in a very large pot with plenty of headroom. Fill with water to cover and then add a few extra inches of water; salt the water. Bring to a boil over high heat. Adjust heat and vigorously simmer until potatoes are tender when pierced with a knife, about 20 minutes or until done.

Meanwhile, warm 3 cups (720 ml) of the milk (or half and half if you want richer mashed potatoes) with the 1/2 cup (113 g) of butter.

Butter the inside of your slow cooker at this time, as well.

Drain well in a colander. Return potatoes to the pot over low heat and toss them around a few times to dry out a bit.

If you are going to mash with a hand-held potato masher you will proceed right in the pot. If you are going to use a ricer or food mill, you will do that right in the slow cooker.

Using Hand-Held Potato Masher: Use a potato masher to begin mashing the potatoes right in the cooking pot, adding the warmed milk and melted butter. Add additional milk if necessary and keep mashing to achieve desired texture. You want them a little looser than usual, as they will dry out a tad in the slow cooker. Taste and season well with salt and pepper. Transfer to slow cooker. Dot potatoes with the remaining 3 tablespoons of butter. Cover the slow cooker and set on warm for up to 4 hours.

Using Ricer or Food Mill: Place ricer or food mill over slow cooker. Add potatoes to ricer or food mill and press potatoes into slow cooker. Clean out skins from food mill as you go. Once all the potatoes are in the slow cooker, add warmed milk and melted butter and use a balloon whisk to bring everything together. Add additional milk if needed, whisking it in well. You want the mashed potatoes little looser than usual, as they will dry out a tad in the slow cooker. Taste and season to taste with salt and pepper. Dot potatoes with the remaining 3 tablespoons of butter. Cover the slow cooker and set on warm for up to 4 hours.