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Gruyere Potato Gratin is the perfect potato side dish for a holiday meal: luxurious, rich and creamy, your guests will love it!

Gruyère Potato Gratin

Adapted from Epicurious. For the most attractive gratin, you will want to put the casserole under the broiler, in which case be sure to use a broil-safe casserole dish.
Author TheSpicedLife


  • 1 clove garlic, smashed
  • 1 T unsalted butter, room temperature
  • 2 small-medium onions, roughly chopped
  • 6 cloves garlic, chopped
  • 2 1/2 cups heavy cream
  • 1 T kosher salt
  • 1 T freshly ground black pepper
  • 1 T thyme leaves
  • 4 lbs russet potatoes, scrubbed and peeled, thinly sliced on a mandoline or in food processor
  • 10 oz Gruyere, shredded, divided
  • 1 oz Parmesan, finely grated


  1. Rub the smashed garlic all over the inside of a 9X13 gratin or casserole dish (see notes above about broiling). Then rub the tablespoon of butter all of the inside of the dish as well. Set aside.
  2. Preheat the oven to 325 F.
  3. Place the onions, minced garlic, heavy cream, salt, pepper and thyme leaves in a medium saucepan. Bring to a boil and then simmer gently for 20 minutes. Do not let it boil hard or you risk the cream breaking.
  4. Let the cream sauce cool for about 5 minutes when it is done. Transfer it to a blender. Add 8 ounces of shredded gruyère cheese. Leave the hole at the top of the blender lid open, and cover it loosely with a towel. Blend until smooth.
  5. Fan the potato slices out as in an accordion, tilting up, so that the tops will crisp a bit under the broiler. Fill in any gaps with extra slices of potatoes. Pour the cheese and cream sauce over the potato slices.
  6. Cover the dish tightly with foil. Bake for 75-80 minutes, or until the potato slices are tender.
  7. Sprinkle the remaining gruyère and the grated parmesan cheese over the top of the casserole. Place under the broiler, now uncovered, and broil until the top is bubbling, browned and a little crispy, about 5-10 minutes.
  8. Let stand for 5 minutes before serving.