Step 1

Preheat oven to 350ºF degrees.

Step 2

In a saucepan, combine the milk, heavy cream, garlic, nutmeg, salt, pepper and herbs. Bring to a simmer then remove from heat. Cover and let it steep for several minutes to infuse the milk/cream with all the flavors.

Step 3

In the meantime, peel and slice the potatoes 1/8-inch thick using a mandoline or food processor. As you slice them, place them in the milk mixture to prevent them from browning.

Step 4

If you haven't yet, grate the cheese. Take 1/4 cup of the grated Gruyere and combine with the parmesan. Reserve.

Step 5

Grease a 11-inch gratin dish with the butter. Drain the potatoes, saving the infused cream in a bowl. Discard the herbs and garlic.

Step 6

Start assembling the dish. Add a layer of the infused cream, followed by a layer of potatoes and a layer of Gruyere cheese. Season lightly with salt and pepper. Repeat layering the potatoes, cream and cheese until all potatoes have been used, always seasoning. If there's any cream left, you can pour it over the top. Top with the reserved parmesan and Gruyere cheese.

Step 7

Bake in the preheated oven until the potatoes are tender and the top is golden brown and bubbly, about 45 to 55 minutes. If you notice that the top is browning too quick, you can cover with foil. If you like, you can increase the heat at the end or pop the dish under the broiler for a deep brown color.

Step 8

Let it rest for 5 minutes before serving. You can garnish with fresh thyme leaves, if desired.