Ingredients:

  • 3 lbs Russet or Yukon Gold potatoes (peeled and sliced 1/8 inch thick)
  • 1 small yellow onion (paper-thinly sliced)
  • 4 tbsp Unsalted butter
  • 1/4 cup All-purpose flour
  • 2 cups Whole milk
  • 1 cup Heavy cream
  • 3 cloves Garlic (minced)
  • 1 tsp Fresh thyme leaves
  • 1 tsp Salt
  • 1/2 tsp White pepper
  • 1/4 tsp Ground nutmeg
  • 1.5 cups Sharp cheddar or Gruyere
  • 2 tbsp Fresh chives (finely chopped)

Instructions:

  1. Peel the potatoes and use a mandoline to slice them into uniform 1/8-inch rounds. Submerge the slices in cold water briefly to remove excess surface starch, then pat them completely dry.
  2. In a large heavy-bottomed saucepan, melt the butter over medium heat. Whisk in the flour for 1-2 minutes until nutty and pale. Gradually stream in the milk and cream, whisking constantly to prevent lumps.
  3. Add the minced garlic, thyme, salt, white pepper, and nutmeg to the sauce. Simmer for 3-5 minutes until the sauce is thickened enough to coat the back of a spoon.
  4. Layer half of the dried potato slices and sliced onions into a greased 9x13 inch baking dish. Pour half of the cream sauce over the layer.
  5. Add the remaining potatoes and onions, followed by the rest of the sauce. Cover the dish tightly with foil.
  6. Bake in a preheated oven at 400°F (204°C) for 30 minutes. Remove the foil, sprinkle with the shredded cheese, and bake for an additional 15 minutes until the top is mahogany-gold and potatoes are tender.
  7. Let the dish rest for 10 minutes to allow the sauce to set before garnishing with fresh chives and serving.