Ingredients:

  • 2.5 lbs (1.1 kg) Yukon Gold potatoes, peeled, thinly sliced
  • 1 teaspoon kosher salt
  • ½ teaspoon freshly ground black pepper
  • 4 tablespoons (57g) unsalted butter
  • 2 cloves garlic, minced
  • ¼ cup (30g) all-purpose flour
  • 3 cups (720ml) whole milk
  • ½ cup (120ml) heavy cream
  • ½ teaspoon salt
  • ¼ teaspoon freshly ground black pepper
  • ⅛ teaspoon ground nutmeg
  • 1 cup (100g) shredded Gruyere cheese (optional)
  • ½ cup (50g) shredded Parmesan cheese (optional)

Instructions:

  1. Slice the potatoes thinly and evenly. Toss with salt and pepper in a large bowl.
  2. Melt butter in a saucepan. Add garlic and cook until fragrant. Whisk in flour and cook for 1-2 minutes to form a roux.
  3. Slowly whisk in milk until smooth. Add heavy cream, salt, pepper, and nutmeg.
  4. Bring the sauce to a simmer, stirring constantly, until it thickens enough to coat the back of a spoon (about 5-7 minutes).
  5. Spread a thin layer of sauce in the bottom of the baking dish. Arrange a layer of potato slices, slightly overlapping. Top with a layer of cheese (if using) and drizzle with more sauce. Repeat layers until all potatoes are used, ending with a layer of sauce and cheese.
  6. Cover the baking dish with foil and bake in a preheated oven at 375°F (190°C) for 30 minutes.
  7. Remove the foil and bake for another 20-30 minutes, or until the potatoes are tender and the top is golden brown and bubbly. Test with a fork - potatoes should be easily pierced.
  8. Let the scalloped potatoes rest for 10-15 minutes before serving. This allows the sauce to thicken slightly.