Ingredients:

  • 2 lbs (900g) Yukon Gold potatoes, peeled, thinly sliced
  • 1 teaspoon (5g) kosher salt
  • ½ teaspoon (2.5g) freshly ground black pepper
  • 2 tablespoons (30ml) unsalted butter
  • 2 tablespoons (15g) all-purpose flour
  • 2 cups (475ml) whole milk
  • 1/4 teaspoon (1.25g) ground nutmeg
  • 1 clove garlic, minced
  • 1/2 teaspoon (2.5g) kosher salt
  • 1/4 teaspoon (1.25g) freshly ground black pepper
  • 1 cup (100g) Gruyère cheese, grated
  • ½ cup (50g) Parmesan cheese, grated

Instructions:

  1. Slice potatoes thinly using a mandoline or a sharp knife. Toss with salt and pepper.
  2. Melt butter in a saucepan over medium heat. Whisk in flour and cook for 1-2 minutes to form a roux.
  3. Gradually whisk in milk, ensuring no lumps form. Add nutmeg, minced garlic, salt, and pepper. Bring to a simmer, stirring constantly, until the sauce thickens (about 5-7 minutes).
  4. Lightly grease the baking dish. Arrange a layer of potato slices on the bottom. Ladle some of the cream sauce over the potatoes, spreading evenly. Sprinkle with a bit of Gruyère and Parmesan. Repeat layers until all potatoes and sauce are used, finishing with a generous layer of cheese on top.
  5. Bake in a preheated oven at 375°F (190°C) for 50-60 minutes, or until the potatoes are tender and the cheese is golden brown and bubbly. A knife should easily pierce the potatoes.
  6. Let rest for 10-15 minutes before serving. This allows the sauce to thicken slightly and the dish to cool.