- 2 tbsp unsalted butter
- 4 lbs medium Yukon Gold potatoes
- 1/2 cup fresh shredded Gruyère cheese
- 1/2 cup fresh shredded sharp white cheddar cheese
- 1 cup fresh shredded Parmesan cheese
- 5 cloves garlic
- 1 medium bunch fresh thyme
- 2 1/4 cups heavy cream
- 1 tsp kosher salt
- 1 tsp freshly ground black pepper
- 1/4 tsp ground nutmeg
- Preheat oven 350°F. Rub 2 tablespoons unsalted butter on the bottom and sides of a cast-iron or ovenproof skillet.
- Peel 4 pounds medium Yukon Gold potatoes. Use a mandoline or a sharp knife to thinly slice 1/8- to 1/4-inch thick.
- Now, grate 1/2 cup Gruyère, 1/2 cup sharp white cheddar cheese and 1 cup Parmesan cheese. Mince the garlic cloves and pick the leaves from 1 bunch fresh thyme and finely chop.
- Add 2 1/4 cups heavy cream, 1 teaspoon kosher salt, 1 teaspoon black pepper, and 1/4 teaspoon ground nutmeg to the bowl and stir to combine. Transfer half of the mixture to the skillet and spread into an even layer.
- Next: arrange the potato slices in a spiral shape in the skillet, working your way from the outside towards the center: Stack a handful of larger similar-sized slices together, then place the stack vertically in the skillet so that you can see the edges of all the slices, nestling them into the cream mixture slightly. Continue stacking and arranging, using the larger slices first and then working your way down in size so the smaller ones are in the center
- Pour the remaining cream mixture evenly over the potatoes. The cream should come about 1/2 inch to the top of the skillet. If you have too much, don’t use it all. Place the skillet on a rimmed baking sheet.
- Bake until the top is deep golden brown and the potatoes are tender, 1 hour 50 minutes. Check after an hour – if the top is already browned, loosely cover the top with aluminum foil and continue baking. Let cool for 10 minutes before serving. Garnish with more fresh thyme leaves if desired.