Ingredients:

  • 2.5 lbs Yukon Gold potatoes, sliced 1/8-inch thick
  • 1 lb leeks, white and light green parts only, cleaned and sliced
  • 3 tbsp unsalted butter
  • 2 cups heavy whipping cream
  • 3 cloves garlic, smashed and peeled
  • 4 sprigs fresh thyme
  • 1 bay leaf
  • 1.5 tsp kosher salt
  • 0.5 tsp freshly cracked black pepper
  • 1 pinch freshly grated nutmeg
  • 1.5 cups Gruyère cheese, shredded
  • 0.25 cup Parmigiano-Reggiano, freshly grated

Instructions:

  1. Clean the leeks by slicing them into rounds and submerging in cold water to remove grit; scoop out and pat dry.
  2. Melt butter in a large skillet over medium heat. Add leeks and a pinch of salt, sautéing for 8–10 minutes until softened and blonde-caramelized.
  3. In a small saucepan, combine heavy cream, garlic, thyme, bay leaf, salt, pepper, and nutmeg. Bring to a simmer, then remove from heat and let steep for 10 minutes.
  4. Grease a 9x13 inch baking dish. Layer half of the sliced potatoes, spread the sautéed leeks on top, then finish with the remaining potatoes.
  5. Strain the warm cream mixture over the potato layers, discarding the herb and garlic solids.
  6. Cover the dish tightly with foil and bake at 375°F (190°C) for 30 minutes.
  7. Remove foil, sprinkle with shredded Gruyère and Parmesan, and bake for an additional 20–25 minutes until the top is bubbling and mahogany-colored.