Peel the potatoes and cut into uniform 1/2-inch pieces. Place into a 4-quart saucepan and cover with cold water by at least 1 inch. Cover, set over high heat, and bring to a boil. Once boiling, remove the lid, decrease the heat to maintain a simmer, and cook until the potatoes can easily be crushed with a pair of tongs, 15 to 20 minutes. Drain in a colander.
Put the cream, butter, salt, and pepper into the now-empty 4-quart saucepan and place back over the heat until the butter has melted. Remove from the heat and set a food mill fitted with the smallest die on top of the pot. Add 1 cup of potatoes to the mill at a time. Once all of the potatoes have passed through the mill, stir to combine. Taste and adjust the seasoning, if desired. Serve immediately.