Ingredients:

  • 1.36 kg Yukon Gold potatoes, peeled and thinly sliced
  • 15 g Unsalted butter (for greasing the dish)
  • 56 g Unsalted butter
  • 30 g All-purpose flour
  • 710 ml Whole milk, room temperature
  • 225 g Sharp Cheddar cheese, shredded
  • 50 g Parmesan cheese, freshly grated
  • 6 g Garlic powder
  • 6 g Salt (plus more to taste)
  • 1 g Black pepper
  • 1 g Ground nutmeg
  • 8 g Fresh parsley, chopped for garnish

Instructions:

  1. Using a mandoline or knife, slice potatoes into 1/8-inch rounds. If you're nervous about the mandoline, just aim for consistent thickness.
  2. Rub the interior of your baking dish with butter to ensure no sticking.
  3. Arrange half of the potato slices in the bottom of the dish, overlapping them slightly like shingles. Sprinkle with half of the salt, pepper, and garlic powder. Repeat with the remaining potatoes.
  4. Melt butter in a saucepan over medium heat. Whisk in the flour and cook for 1–2 minutes until it smells slightly nutty but hasn't browned.
  5. Slowly pour in the milk, whisking constantly. Continue cooking until the sauce thickens enough to coat the back of a spoon.
  6. Remove from heat. Stir in the shredded Cheddar and Parmesan until completely melted.
  7. Pour the cheese sauce evenly over the layered potatoes. Bake for 80 minutes until the top reaches a mahogany color and the sauce is bubbling.