Cheesy, crispy and rich tasting, potatoes au gratin make for an indulgent and delectable side dish. Often confused with scalloped potatoes, potatoes au gratin are made of thinly sliced potatoes, cooked gently in cream and baked often with butter, cheese or bread crumbs to make a crispy topping. Scalloped potatoes, in turn, are much less rich, as they are only sliced potatoes cooked in milk. While the dish requires some preparation, potatoes au gratin can easily be made at home.
Potato Choice and Preparation
Choose a waxy or all-purpose potato to make potatoes au gratin, as starchy potatoes do not hold up well after they’re cooked. Red skin and Yukon Gold potatoes are excellent choices for potatoes au gratin, as are Kennebec potatoes, which are white skinned and fleshed. Choose potatoes that have smooth, unblemished peels and avoid those with a green tinge to their skin. If you want to, peel your potatoes after carefully scrubbing them so they’re free of dirt. Remove the eyes from the potatoes, and slice them into 1/8-inch thick slices. Use a mandoline or a food processor to create even slices if you’re unable to cut the potatoes thinly enough.
Heat a blend of milk and cream, use a 1-to-1 ratio, in a saucepan, along with a clove of smashed garlic, some fresh thyme and a small amount of chopped shallot. Heat until the mixture begins to bubble, and then strain, removing the added seasonings. Stir in a sprinkle of freshly grated nutmeg. For every pound of sliced potatoes, use 1-cup of sauce. Season your sauce to taste with salt and pepper.
To bake potatoes au gratin, preheat the oven to 375 degrees Fahrenheit, and butter or oil a baking dish that can comfortably fit all of your potatoes and sauce. Place a thin layer of potatoes in the dish, drizzling it with cream sauce. Add another layer, and drizzle cream sauce on top until all the potatoes and sauce are used up. As optional ingredients, scatter seasoned breadcrumbs and shredded cheese on top before placing your gratin in the oven. Use a 1-to-2 ratio of cheese to potato, and use breadcrumbs as desired. Bake for around 1 hour, until the top has browned and the potatoes are fork tender. Let the dish rest, uncovered, for 5 minutes before serving.
Potatoes au gratin can also be made in a slow cooker or on the stove, however, you won’t get the browning that comes from oven baking. One option is to start your gratin in the slow cooker or the stove — cooking on the low setting in a slow cooker for 7 to 8 hours or on medium-high heat for about 10 minutes — and then finishing the gratin in the oven. Bake the pre-cooked gratin in the oven for 10 minutes at 300 F to make it brown and crispy.
Serving, Variations and Food Safety
Serve potatoes au gratin alongside poached fish or roast turkey or chicken, as the richness of the dish means it goes best with simply cooked meats and vegetables. While the classic gratin has only thyme and nutmeg as seasoning, feel free to add chopped ham, canned corn or bacon for a more luxurious side dish. As a casserole dish, potatoes au gratin needs to be cooked until the internal temperature reads 165 F. Leftover gratin should be cooled quickly and stored in sealed containers in the fridge or freezer. It can be safely eaten after being reheated to an internal temperature of 165 F.
References and Resourcesthe kitchn: Sixteen Kinds of Potatoes
Joy of Cooking; Irma S. Rombauer
The Guardian: How to Cook the Perfect Gratin Dauphinois
Fine Cooking: Classic Potato Gratin
BBC Good Food: Ultimate Gratin Dauphinois
Betty Crocker: Slow Cooker Cheesy Ham au Gratin
The New York Times: Fast Potato Gratin
U.S. Department of Agriculture: Safe Minimum Internal Temperature Chart
U.S. Department of Agriculture: Leftovers and Food Safety
Food and Wine: Rich and Creamy Potato Gratin