For me, Easter provides a wonderful excuse to make a really big lunch for my family and friends, and my menu almost always hinges on roast leg of lamb, which is a traditional centerpiece for many Easter meals. This year, when planning out all of my side dishes, I was inspired by this foodpickle thread to revisit a classic from my cooking school days: pommes dauphinoise, which are also known as potatoes au gratin. I had to make this dish countless times over the course of my nine months while I was at Le Cordon Bleu in London, to the point that I could probably have made it in my sleep. It's simple but its charms are many, and I'm glad I've returned it to my table after all these years. Once you make it and give it a taste, you and your guests will soon see the appeal as well.
Many people insist on using heavy cream when you're making any kind of gratin, but I'm loyal to the method my cooking instructors taught me, which is to use garlic-infused whole milk. With the cheese and the starch of the potatoes, the dish is by far rich enough for my tastes, and I find that the cream mutes the delicate flavor of the Gruyère and garlic. If you have a mandoline, then I recommend using it for this recipe when you're prepping the potatoes. The thinner and more evenly you slice your potatoes, the more delicate–and lovely–the finished gratin will be. —Merrill Stubbs
Heat the oven to 425°F. Pour the milk into a small heavy saucepan. Peel and smash 1 garlic clove and add to the milk. Warm over medium-low heat until the milk starts to bubble at the edges. Remove from the heat and let steep.
Peel the remaining garlic clove, cut in half, and rub the cut sides around the inside of an oval gratin dish about 9 inches long and 2 inches deep. Rub 1 tablespoon of the butter inside of the baking dish.
Peel the potatoes and cut into ⅛-inch-thick slices (I use a mandoline to get them nice and even), laying the slices on a kitchen towel to drain. Layer about one-third of the potatoes in the bottom of the baking dish, fanning them into concentric, overlapping circles. Season with salt and pepper; sprinkle with one-third of the cheese. Repeat with 2 more layers of potatoes, salt. pepper, and cheese, making the top layer as neat and tidy as you can.
Remove the garlic clove from the hot milk. Pour the milk evenly over the potatoes. Dot the top of the potatoes with the remaining 1 tablespoon of the butter. Bake the gratin for about 30 minutes, until browned and bubbly. Let cool for 5 minutes before serving.