Ingredients:

  • 2.5 lbs (1.1kg) Yukon Gold potatoes, peeled and thinly sliced
  • 1 tsp (6g) kosher salt
  • 1/2 tsp (3g) black pepper
  • 4 tbsp (56g) unsalted butter
  • 1/4 cup (30g) all-purpose flour
  • 2 cups (480ml) whole milk
  • 1 cup (240ml) heavy cream
  • 3 cloves (15g) garlic, minced
  • 2 cups (225g) sharp cheddar cheese, grated
  • 1 cup (115g) Gruyère cheese, grated
  • 1/4 tsp (1g) ground nutmeg
  • 1/2 cup (50g) Parmesan cheese, grated
  • 1 tbsp (4g) fresh thyme leaves
  • 2 tbsp (30g) melted butter

Instructions:

  1. Using a mandoline or knife, slice potatoes into 1/8-inch (3mm) rounds. Toss the slices with salt and pepper in a large bowl and let sit for 5 minutes.
  2. Melt 4 tbsp butter in a saucepan over medium heat. Whisk in flour and cook for 1-2 minutes until nutty but not browned.
  3. Slowly whisk in milk and heavy cream. Simmer gently, stirring constantly, until the sauce thickens enough to coat the back of a spoon.
  4. Stir in minced garlic and nutmeg. Turn heat to low and fold in the cheddar and Gruyère until the sauce is glossy and smooth.
  5. Grease a 9x13 inch baking dish. Layer 1/3 of the potatoes, followed by 1/3 of the cheese sauce. Repeat twice more.
  6. Cover the dish tightly with foil. Bake at 375°F (190°C) for 45 minutes.
  7. Remove foil. Brush the top with melted butter and sprinkle with Parmesan and thyme. Bake uncovered for 30-45 minutes until bubbling and mahogany-colored.