Take the Balme lift. hike round the side of the Balme, away from the Aiguille, and following the tracks you end up in another Balme-esque valley, but this time one devoid of lifts or pistes. You are then free to ski down to Lac des Confins, about 900m below, from where you can get the bus to La Balme and go back and do it all over again.
Large open bowl. Not very steep but you can find a lot of fun terrain here.