Crispy potatoes au gratin are thinly sliced potatoes stacked on their side, instead of layered, for the creamiest potatoes with crispy edges in every bite. A simple make-ahead side dish.Those crispy edges are the best! Potatoes au gratin with gruyere is one of those dishes that sound super fancy but you’ll be amazed at how simple and easy this recipe is. You can put this together in about 20 minutes depending on how fast you can peel potatoes! It's great for a Holiday meal.