Combine the cream, water, potatoes, 1 tablespoon of kosher salt, and 1 teaspoon of black pepper in a large saucepan set over medium heat.
2 cups heavy cream, 3 cups water, 2 tablespoons kosher salt, 1½ teaspoon ground black pepper, 3 pounds Yukon Gold potatoes
Bring just to a boil, reduce heat to low, and simmer for 15-25 minutes, or until the potatoes are fork-tender.
Drain the potatoes in a colander set over a medium-sized heatproof bowl (reserve the potato milk/water).
Return the potatoes to the pan and set the heat to medium-low. Stir gently until the excess moisture evaporates from the potatoes, about 1 minute.
Add the butter, 1½ teaspoons kosher salt, and ½ teaspoon black pepper. Mash the potatoes until smooth and creamy (or fluff adding some of the reserved potato milk-water, when/if necessary. (Note: If not serving the potatoes immediately, save about 1 cup of the milk-water to add before serving. Be sure to add the milk-water in ¼-cup increments to ensure the potatoes stay fluffy. No one likes watery mashed potatoes.)
½ cup unsalted butter
Transfer potatoes to a serving bowl, dot with 3-4 tabs of butter (or drizzle with melted butteand garnish with parsley or cheese, if desired.
Chopped fresh parsley, Freshly grated cheese, Extra butter