Peel sweet potatoes, quarter lengthwise, and cut crosswise into 1/4-inch thick slices.
Combine sweet potatoes, butter, cream, sugar and salt in large saucepan and cook, covered, over low heat, stirring occasionally, until the sweet potatoes fall apart when poked with a fork, about 35-45 minutes.
Off heat, mash the sweet potatoes in saucepan with potato masher (you could also use ricer or food mill). Stir in pepper, serve immediately. Enjoy!