Scalloped Potatoes in Cast Iron

Author Notes

Scalloped potatoes used to mean something else entirely. In the late 1800s, this term referred to mashed potatoes, covered in grated cheese, and baked in scallop shells. By the following century, the recipe moved into a baking dish, and eventually it evolved into the creamy gratin we expect today.

Most contemporary American scalloped potatoes recipes look a lot like the French gratin dauphinois. A version of this recipe appears in the famous Julia Child cookbook Mastering the Art of French Cooking. There, she translates gratin dauphinois as “scalloped potatoes with milk, cheese, and a pinch of garlic.” It’s Julia’s excellent version that we used as a jumping-off point in developing our best scalloped potatoes recipe.

Like gratin dauphinois, scalloped potatoes include thinly sliced potatoes, milk and/or heavy cream, and a top layer that’s golden and crispy from the oven. But, there is actually little consensus on whether scalloped potatoes should include cheese, and how scalloped potatoes differ from a gratin or casserole. Several sources insist that scalloped potatoes shouldn’t include cheese, yet the majority of popular scalloped potatoes recipes on the internet do include cheese.

After weighing the pros and cons, we decided to add cheese—because scalloped potato enthusiasts expect as much, and roasted potatoes taste delicious with a layer of bubbly cheese on top. We considered using Gruyère or cheddar and, after trying both, went with Gruyère, due to its nutty-sweet flavor and A+ melting. If you can’t find Gruyère (or don’t like it), Comté or a quality Swiss cheese are also great options; you just want a cheese that’s deeply savory, pleasantly assertive, and doesn’t get too oily as it melts.

When it comes to potatoes, we chose to use Yukon Golds rather than starchier Russets. While Russets can break apart easily when sliced and baked, Yukons hold up well, and have a denser, creamier texture.

Now, what to cook these potatoes in? Milk can curdle when it simmers in the oven. The taste remains good, but it’s visually unappealing. Some recipes solve this problem by making a béchamel sauce, or milk gravy (milk thickened with a roux of butter and flour). We chose to simplify the process by using heavy cream instead. It yields a rich, savory flavor, is less work, and is gluten-free.

You could call it a day with just the cream, but a couple bonuses go a long way. For added flavor, we infuse it with a bay leaf and some minced garlic. Though these ingredients get strained out and discarded, their subtle flavor perfumes the finished dish. Fresh thyme is also used to add depth, as it’s sprinkled among the layers of potato. Of course, you can use rosemary or sage if you prefer, but we found that fresh thyme works best to compliment the potatoes without overwhelming the dish.

One final important note: When the scalloped potatoes come out of the oven, you should wait 20 to 30 minutes before serving. This is a dish that needs some time to settle, and actually tastes better warm than hot.
—Josh Cohen