Pour water into a saucepan. Place a large steamer basket into the saucepan over (not touching) the water, and place the potatoes into the basket.
Bring the water to a boil. Reduce heat to a simmer, cover the pan and basket with a lid, and steam potatoes until tender in the center, about 20 minutes.
A skewer inserted into a potato should easily pierce the center. Using tongs to hold hot potatoes, peel them, and set aside. Reserve potato cooking water.
Place 1 cup of cream and the butter into the work bowl of a large stand mixer fitted with mixing paddle, and start the machine on low speed. Mix until the cream and butter are blended; add potatoes, and beat until thoroughly mixed.
As potatoes mash, gradually pour in remaining cup of cream. If potatoes are too stiff, beat in reserved potato cooking water, 1 tablespoon at a time. If potatoes are too runny, beat in instant mashed potato flakes, 1 tablespoon at a time, until you reach desired consistency. Season to taste with salt and white pepper.