Herbed Potato Gratin

1 1/2 cups (12 fl. oz.) heavy cream
1 garlic clove, minced
1 tsp chopped fresh rosemary
1 tsp chopped fresh thyme
1/2 tsp chopped fresh sage
Salt and freshly ground pepper, to taste
2 lb russet potatoes
1/2 onion, thinly sliced
3 cups grated Gruyère cheese
1/4 cup grated Parmesan cheese

1. Preheat an oven to 375. Butter an 11-inch baking dish.

2. In a large saucepan over medium heat, combine the cream, garlic, rosemary, thyme, sage and a pinch each of salt and pepper. Bring just to a boil, then remove from the heat and set aside.

4. Peel the potatoes. Using a mandoline or very sharp knife, cut the potatoes into slices about 1/8 inch thick. Gently stir the potato slices into the cream mixture.

5. Arrange one-third of the potato slices, slightly overlapping, on the bottom of the prepared dish. Sprinkle generously with salt and pepper, half of the onions and 1 cup of the Gruyère. Repeat, using another one-third of the potato slices, salt and pepper, all the remaining onions, and another 1 cup of the Gruyère. Top with the remaining potatoes and sprinkle with salt and pepper again. Using a large, flat spatula, gently press on the potatoes to compact them. Pour any cream mixture remaining in the saucepan over the potatoes and sprinkle evenly with the remaining 1 cup Gruyère and the Parmesan.

6. Cover the dish with aluminum foil and bake until the potatoes are tender when pierced with a sharp knife, about 45-60 minutes. Remove the foil and bake until the gratin is golden brown and bubbly, about 20-30 minutes more. Let the gratin rest for 10 minutes, then use a spatula to cut it into squares and serve immediately. Serves 6 to 8.

(adapted from Williams-Sonoma)