Preheat oven to 400 degrees. On a lightly floured surface, roll dough into a 14-inch round that is 1/8 inch thick. Fit the dough into a 9-inch pie plate. Transfer to refrigerator to chill for 30 minutes.
In a large bowl, combine plums, sugar, flour, nutmeg, and lemon juice. Toss to combine. Mound plums in the lined pie plate. Dot with butter, and fold the pastry up over the fruit. Transfer to refrigerator to chill for 30 minutes.
Brush the pastry with cream, and sprinkle with granulated sugar. Bake until the plums are tender, the juices in the center of the pie are bubbling, and the pastry is golden brown, about 40 minutes. Let cool slightly before dusting with confectioners' sugar for serving.