Ingredients:
- lbs Russet or Yukon Gold Potatoes, peeled
- cups Heavy Cream (Double Cream)
- cup Whole Milk
- large cloves Fresh Garlic, finely minced
- tablespoon Fresh Thyme Leaves
- /4 teaspoon Freshly Grated Nutmeg
- teaspoon Kosher or Sea Salt (plus extra for seasoning layers)
- /2 teaspoon Freshly Ground Black Pepper
- cup Freshly Grated Gruyère or Comté Cheese (Optional)
- tablespoon Unsalted Butter, for greasing
Instructions:
- Preheat oven to 375°F (190°C). Thoroughly grease the 9x13 inch baking dish with butter. Peel potatoes and slice very thinly (ideally 1/8 inch or 3mm thick using a mandoline).
- In a medium heavy-bottomed saucepan, combine cream, milk, minced garlic, thyme leaves, nutmeg, salt, and pepper. Bring the mixture to a bare simmer over medium heat, stirring gently. Remove immediately from heat and let steep for 10 minutes.
- Strain the cream mixture through a fine-mesh sieve into a bowl, discarding the thyme leaves and large garlic pieces. If the cream mixture has cooled significantly, reheat slightly until warm.
- Arrange a thin, overlapping layer of potato slices evenly across the bottom of the prepared dish. Sprinkle lightly with salt and pepper.
- Ladle about 1/4 of the warm cream mixture evenly over the potatoes. Add the next layer of potatoes, ensuring even coverage. Continue layering, alternating potatoes and cream, until all potatoes and liquid are used. The liquid should almost cover the top layer.
- Cover the dish tightly with foil. Bake for 45 minutes. This steaming stage ensures the potatoes cook through without drying out.
- Remove the foil. If using cheese, sprinkle it evenly over the top. Increase the oven temperature to 400°F (200°C) or switch to the broiler setting (watch carefully!). Bake uncovered for another 15–20 minutes, or until the top is deep golden brown and bubbling vigorously.
- Test for doneness by inserting a thin skewer—it should slide through with almost no resistance. Remove from the oven and let rest for 10 minutes before scooping and serving.