Make this. Just follow SmittenKitchen's recipe and do it. (3 lb chard = 5 good-sized bunches; 2 lb yams = 3 medium ones; 1 c cream + 1 c 1% milk worked just fine.)
See how little leftovers there are, compared to all those mujadarra leftovers? They're both way tastier than they look, but this gratin especially so. Totally worth chopping all those greens.