👨‍🍳 Instructions

1. 1

   Preheat oven to 375°F (190°C). Grease a 9x13 inch baking dish with butter.

   💡 Tip: Using a greased dish prevents sticking and helps create a nice crust.
2. 2

   Peel the potatoes and slice them thinly (about 1/8 inch thick) using a mandoline or a sharp knife. Set aside.

   💡 Tip: Thin, even slices ensure consistent cooking.
3. 3

   Melt 2 tablespoons of butter in a large skillet over medium heat. Add the sliced leeks and sauté until softened, about 5-7 minutes. Add the minced garlic and cook for another minute until fragrant.

   💡 Tip: Sautéing the leeks brings out their sweetness and tenderizes them.
4. 4

   In a medium bowl, whisk together the heavy cream, milk, salt, pepper, nutmeg, and optional herbs. Stir in 2/3 of the grated cheese.

   💡 Tip: Warming the cream mixture slightly can help it combine better.
5. 5

   Layer half of the sliced potatoes in the prepared baking dish. Top with half of the sautéed leek and garlic mixture. Pour half of the cream mixture over the potatoes and leeks. Sprinkle with some of the remaining cheese.

   💡 Tip: Layering ensures even distribution of ingredients and flavors.
6. 6

   Repeat the layering process with the remaining potatoes, leeks, cream mixture, and cheese.

   💡 Tip: Ensure the top layer of potatoes is well-covered with the cream mixture.
7. 7

   Cover the baking dish tightly with aluminum foil. Bake for 30 minutes.

   💡 Tip: Covering with foil steams the potatoes and prevents the top from browning too quickly.
8. 8

   Remove the foil and bake for another 20-25 minutes, or until the potatoes are tender when pierced with a fork and the top is golden brown and bubbly.

   💡 Tip: Uncovering allows the gratin to brown and crisp up.
9. 9

   Let the gratin rest for 10 minutes before serving. This allows the sauce to set slightly.

   💡 Tip: Resting makes the gratin easier to slice and serve.