Preheat oven to 400 degrees F. Wash, prick a few times with a fork ,and then bake potatoes until very tender, about 1 hour. Cool slightly, then cut off the top 2/3's the way up the potato. Carefully scoop out as much of the flesh as you can and place in a bowl. Reserve shells. Mash potatoes until smooth, and then vigorously whip - this will lighten potatoes and increase their volume -in remaining ingredients. Spoon or pipe mixture back into the potatoes. Bake stuffed potatoes until nicely browned, about 25 to 30 minutes. If desired, sprinkle with a few more chopped green onions before serving.