Ingredients:

  • 2 lbs (900 g) Yukon Gold or Russet potatoes, peeled and thinly sliced (~1/8 inch / 3 mm)
  • 2 cups (480 ml) whole milk
  • 1 cup (240 ml) heavy cream
  • 3 tablespoons (45 g) unsalted butter
  • 3 cloves garlic, minced
  • 1 teaspoon salt
  • ½ teaspoon freshly ground black pepper
  • ½ teaspoon fresh thyme leaves (optional)
  • 2 cups (200 g) shredded sharp white cheddar cheese (or Gruyère for nuttier flavor)
  • ¼ cup (25 g) grated Parmesan cheese (for topping)
  • 2 tablespoons (15 g) all-purpose flour (for thickening sauce)

Instructions:

  1. Prepare potatoes: Peel and slice potatoes evenly using a mandoline or sharp knife. Set aside in cold water to prevent browning.
  2. Make the cheese sauce (béchamel base): Melt butter in a saucepan over medium heat. Add minced garlic and sauté until fragrant (about 1 minute). Whisk in flour to form a roux and cook for 1-2 minutes without browning. Slowly whisk in milk and cream, ensuring no lumps. Cook, whisking constantly, until the sauce thickens (about 5-7 minutes). Remove from heat and stir in salt, pepper, and thyme. Stir in 1½ cups shredded cheddar cheese until melted and smooth.
  3. Assemble: Preheat oven to 350°F (175°C). Drain potatoes and pat dry. Layer half the potatoes in a baking dish and pour half the cheese sauce over them. Repeat with the remaining potatoes and sauce, then sprinkle the remaining cheddar and Parmesan cheese on top.
  4. Bake: Cover loosely with foil and bake for 45 minutes. Remove the foil and bake uncovered for an additional 15 minutes until the cheese is golden and bubbly, and the potatoes are tender.
  5. Rest and serve: Let the dish cool for 10 minutes before serving to allow the sauce to thicken slightly.