Place the potatoes in a pot of salted water and bring to a boil. Reduce the heat to a simmer and cook the potatoes until fork tender, about 12 to 15 minutes. Remove the pan from the heat and drain. Place the potatoes back in the pot and return to the heat. Stir the potatoes, constantly, for 2 to 3 minutes to dehydrate the potatoes. Remove the potatoes from the heat. Add the butter. Using a hand-held masher, mash the butter into the potatoes. Add enough cream until desired smoothness is achieved. The potatoes should still be sort of lumpy. Season the potatoes with salt and pepper.