For a hearty side dish, make Ree Drummond's Perfect Potatoes au Gratin Just before serving, sprinkle on the grated cheese and return it to the oven until the. Mar 28, The main difference between au gratin potatoes and scalloped potatoes are the addition of cheese. Potatoes au gratin usually have Gruyere. Mix remaining cheese and the bread crumbs; sprinkle over potatoes. .. I love cheesy au gratin potatoes but have never made them from scratch, as my Nona.