Potato Gratin

• 2 garlic cloves, smashed or cut in half
• 2 tbsp butter, at room temperature, divided
• 2 cups (500ml) heavy cream
• 4-5 thyme sprigs
• 2 tbsp and 1 tsp thyme leaves
• 2 lb gold potatoes, about 8, well-rinsed
• Kosher salt, such as Diamond Crystal
• Black pepper
• 1 whole nutmeg, for grating
• ⅓ cup (38g) shredded Gruyère

Heat the oven to 375°F. Prepare a 9-by-13-inch baking dish or pan: Sprinkle 1 garlic clove with a pinch of salt and rub it around the bottom and sides of the dish. (Reserve the garlic clove to use in the steeped cream.) Spread 1 tablespoon of butter over the bottom and sides to coat.

Steep the cream: In a small saucepan, combine cream, thyme sprigs, the remaining 1 tablespoon of butter and both garlic cloves. Heat the mixture over medium until the cream starts to steam and ripple. Reduce heat to very low and simmer for 2 minutes. Remove from heat and let steep while you prepare the potatoes.

Remove any eyes from the potatoes, but do not peel them. Slice the potatoes crosswise into ⅛-inch-thick slices. (A mandoline is the best tool for this job.) Do not rinse the potatoes after slicing; the starch is important to thicken the cream.

Strain the cream into a liquid measuring cup or other spouted container.

Arrange a single, slightly overlapping layer of potatoes evenly on the bottom of the prepared dish. Drizzle the center with 2 tablespoons of the cream, sprinkle evenly with salt (a scant ½ teaspoon), a few hearty grates of nutmeg and a couple cracks of black pepper. Evenly arrange another layer of potato on top of that layer, drizzle with another 2 tablespoons of cream in the center and sprinkle with another scant ½ teaspoon salt and 2 teaspoons of picked thyme leaves. Repeat each of these layers once more until you have four layers. Arrange the potatoes in a fifth and final layer overlapping in pretty scallop formation. Pour the remaining cream over the top and sprinkle with a final ½ teaspoon of salt and a little nutmeg.

Bake the potatoes, uncovered, for 40 minutes. Meanwhile, combine the Gruyère with remaining 1 tablespoon thyme leaves and set aside.

After 40 minutes, remove from the oven. Sprinkle evenly with the Gruyère mixture and bake for another 10 minutes, until browned and bubbly on top. Let cool in the pan for 20 minutes before serving.