2pounds starchy potatoes (Russet, Maris Piper, or King Edward)
1/2clove unpeeled garlic
4tablespoons unsalted butter
1teaspoon salt
1/8teaspoon black pepper
1cup (4 ounces)grated Swiss or Gruyère cheese (optional)
1cupboiling milk or heavy cream
Instructions
Prepare the Potatoes
Preheat your oven to 425°F (220°C). Peel the potatoes and slice them thinly, about 1/8 inch thick. Place the slices in cold water to prevent discoloration. Drain and pat dry with a towel before use.
Prepare the Baking Dish
Cut the garlic clove in half and rub the cut side all over the inside of a baking dish. Smear the dish with 1 tablespoon of butter to prevent sticking and add flavor.
Layer the Potatoes
Arrange half of the potato slices in the dish. Sprinkle half of the salt, pepper, and grated cheese (if using) over the layer. Dot with 1 tablespoon of butter. Repeat with the remaining potatoes, seasonings, cheese, and butter.
Add the Cream
Pour the boiling milk or cream evenly over the layered potatoes. The liquid should just reach the top layer but not submerge it completely.
Bake the Gratin
Place the dish in the upper third of the preheated oven. Bake for 20–30 minutes, or until the potatoes are tender, the milk is absorbed, and the top is golden brown
Rest and Serve
Allow the gratin to cool for a few minutes before serving. This helps the layers set and makes it easier to portion.