Ingredients:

  • 3 lbs Yukon Gold potatoes, peeled and sliced 1/8 inch thick
  • 1 large yellow onion, shaved into paper-thin rings
  • 2 cups whole milk
  • 1 cup heavy cream
  • 3 tbsp unsalted butter
  • 3 garlic cloves, smashed
  • 4 sprigs fresh thyme
  • 1 tsp kosher salt
  • 1/2 tsp freshly cracked black pepper
  • 1/4 tsp ground nutmeg
  • 1/2 cup freshly grated Gruyère cheese
  • Fresh chives for garnish

Instructions:

  1. Preheat the oven to 350°F (180°C). Note: This moderate temp ensures the potatoes soften before the cheese burns.
  2. Infuse the milk, cream, smashed garlic, and thyme sprigs in a saucepan over medium heat until small bubbles form at the edges.
  3. Steep the liquid off the heat for 10 minutes, then strain out the solids. Note: This removes the woody thyme stems but keeps the flavor.
  4. Whisk the salt, pepper, and nutmeg into the warm infused cream.
  5. Layer one third of the sliced potatoes into the greased baking dish, followed by half of the shaved onions.
  6. Repeat the layers, ending with a final neat layer of potatoes on top.
  7. Pour the cream mixture over the potatoes until they are nearly submerged.
  8. Cover tightly with foil and bake for 45 minutes. Note: The foil traps steam to cook the potato starch.
  9. Remove foil, sprinkle the Gruyère over the top, and bake for another 30 minutes until the top is golden and bubbling.
  10. Rest the dish for at least 15 minutes before serving. Note: This is vital for the sauce to set.