Place potatoes in medium stockpot and add enough water to cover by 2 inches. Place over high heat and bring to a boil. Reduce to a simmer and cook until tender when pierced with the tip of a knife, 15 to 20 minutes. Drain cooked potatoes well.

In a small saucepan, combine rice milk, heavy cream and butter. Place over medium heat until milk is warm and butter is melted.

Pass the potatoes through a ricer back into the stockpot, or use a potato masher. Add rice milk mixture and stir to combine. Season with salt and pepper.