Hasselback Potato Gratin
with Winter Herbs and Fontina

 

This crispy, cheesy, über-decadent casserole is a happy mash-up of a potato gratin and accordion-cut hasselback potatoes. The trick is to thinly slice the potatoes and then arrange them vertically in the baking dish. The result is a gratin with extra crispy edges on top and tender, creamy potatoes below. Instead of a more classic cheese choice like gruyere, here I use a semi-soft cow’s milk cheese called fontina. It melts beautifully and has a buttery, nutty flavor with a bit of honeyed sweetness. This dish is a real crowd-pleaser.

 
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Serves 8 to 10

  • Nonstick cooking spray, for greasing

  • 5 ounces Fontina cheese, shredded

  • 2 ounces finely grated Parmigiano-Reggiano cheese

  • 3 cups heavy cream

  • 1 large shallot, very thinly sliced

  • Kosher salt and freshly ground black pepper

  • 5 pounds russet potatoes (about 6 large potatoes), peeled and sliced 1/8-inch thick on a mandolin slicer (see Note)

  • Small rosemary sprigs and sage leaves, for garnish

  • Flaky sea salt, for sprinkling


    1. Preheat the oven to 400° and grease a 9-by-13-inch baking dish. Set the baking dish on a rimmed baking sheet.

    2. In a large bowl, combine the cheeses. Transfer 1/3 of the cheese mixture to a small bowl and set aside.

    3. To the large bowl, add the cream and shallot and stir to combine. Season with 1 teaspoon of kosher salt and ½ teaspoon pepper. Add the potatoes and toss to coat, using your hands to break up any potatoes that are sticking together. Working with a handful of potatoes at a time (try to get a few slices of shallot and cheese in each handful), arrange the potato slices into neat stacks and place them vertically in the prepared baking dish. Repeat with the remaining potatoes, forming three tightly-packed rows. Tuck a few small rosemary sprigs and sage leaves in between some of the potato slices, then pour the remaining cream mixture evenly over the potatoes until it comes halfway up the sides of the baking dish. You might not need all of it. Sprinkle the top of the casserole with some flaky sea salt and more pepper.

    4. Cover the baking dish tightly with foil and bake for 30 minutes. Remove the foil and continue baking until the top is beginning to brown, about 30 minutes more. Scatter the remaining cheese over the potatoes and return to the oven until the top is crispy and a deep golden brown, about 30 minutes more. Let cool slightly before serving.

     NOTE A mandoline slicer is an incredibly useful tool that can save you from a lot of tedious knife work. They’re available on amazon.com and in most kitchen supply stores. Alternatively, you can use the small slicing disk on a food processor.