Twice Baked Potatoes, "potatoes Suzette"

Bake 6 large potatoes, cut them in half lengthwise, and scoop out and mash the pulp. Add 2 tablespoons butter, 3 tablespoons heavy cream, and 1-well-beaten egg yolk. Beat well and pack into generously buttered potato shells. Finish with a ring of potato rosettes forced through a pastry bag and bake in a hot oven until golden brown. A little Parmesan cheese may be sprinkled over the stuffed potatoes before baking.