01 - Place the potato chunks in a large pot and cover with cold water. Add a generous pinch of salt to the water. Bring to a boil over medium-high heat, then reduce to a gentle simmer.
02 - Simmer the potatoes for 15-20 minutes, or until fork-tender. Test by inserting a fork into a potato chunk—it should slide in easily with no resistance.
03 - Drain the potatoes thoroughly in a colander, then return them to the hot pot. Let them sit for 1-2 minutes to allow excess moisture to evaporate.
04 - Add the butter, warm milk, salt, and pepper to the potatoes. Mash using a potato masher or hand mixer until smooth and creamy. Taste and adjust seasoning as needed.
05 - Transfer to a serving bowl and top with an extra pat of butter if desired. Serve immediately while hot.