
Add 5 pounds peeled and diced Russet or Yukon Gold potatoes and 1 cup water to a 5-quart crockpot. Cover and cook for 4-5 hours on LOW, until the potatoes are very soft.
Add 1 cup warm half and half, ½ cup melted unsalted butter, 1 ½ teaspoon salt, and ½ teaspoon ground black pepper to the soft potatoes, then use a hand masher, hand mixer, or potato ricer to mash the potatoes to your desired consistency. Season with additional salt and pepper to taste. Switch the crockpot to the WARM setting before covering and keeping warm for up to 2 hours.