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Au Gratin Potatoes Recipe

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4.3 from 9 reviews

This classic Au Gratin Potatoes recipe features thinly sliced russet potatoes baked in a rich, creamy blend of heavy cream, milk, Gruyere, and Parmesan cheeses, infused with caramelized onions, garlic, and fresh thyme. The gratin is baked until golden and bubbly, then garnished with fresh chives for an elegant side dish perfect for any occasion.

Ingredients

Vegetables

  • 1 small yellow onion, finely diced
  • 4 cloves fresh garlic, minced
  • 2 ½ lbs. russet potatoes, sliced 1/8-inch thick
  • Chives, for garnish

Dairy

  • 3 tablespoons salted butter
  • 2 cups heavy cream
  • ½ cup milk
  • 2 cups shredded Gruyere cheese
  • ½ cup grated Parmesan cheese

Herbs & Spices

  • 2 teaspoons fresh thyme leaves
  • ¼ teaspoon salt
  • ¼ teaspoon black pepper

Instructions

  1. Preheat Oven: Preheat your oven to 350°F (175°C). This step can be done right away or after caramelizing the onions.
  2. Prepare Cream Mixture: In a medium measuring cup, combine the heavy cream and milk. Temper the mixture by microwaving for 1 minute and then set aside.
  3. Caramelize Onions: In a soup pot over medium heat, add the diced onions and butter. Cook for 10 minutes, stirring often until the onions soften. Reduce the heat to medium-low and continue cooking for another 10-15 minutes, stirring frequently, until they begin to brown and caramelize slightly. Add the minced garlic and fresh thyme leaves; cook for an additional 2 minutes.
  4. Add Cream Mixture: Turn off the heat and allow the pot to cool for 1 minute. Gradually stir in the tempered cream and milk mixture. Turn the heat back on to medium-high, bring the liquid to a boil, then remove from heat.
  5. Incorporate Cheeses and Seasoning: Slowly add the shredded Gruyere and grated Parmesan cheeses to the pot, stirring to allow them to melt smoothly. Stir in salt and pepper to season the sauce.
  6. Slice Potatoes: Using a mandoline or a sharp knife, slice the russet potatoes into 1/8-inch thick pieces to ensure even cooking.
  7. Layer Potatoes and Sauce: Lightly grease a 2.5-quart or 9 x 13-inch baking dish. Arrange one-third of the potato slices evenly on the bottom. Lightly sprinkle a bit of salt over the layer. Pour one-third of the cheese sauce over the potatoes. Repeat this layering process two more times, finishing with sauce on top.
  8. Bake Covered: Cover the dish with foil or a lid and bake in the preheated oven for 1 hour.
  9. Bake Uncovered: Remove the cover and continue baking for an additional 30 minutes until the top is golden and bubbly.
  10. Optional Broil: For extra color, broil the gratin at 425°F for 1-2 minutes. Watch carefully to prevent burning.
  11. Rest and Garnish: Remove the gratin from the oven and let it rest for 5-10 minutes. This resting time allows the sauce to thicken. Garnish with freshly chopped chives before serving.

Notes

  • Using a mandoline slicer ensures uniform potato slices for even cooking.
  • Lightly salting each potato layer seasons the gratin evenly.
  • Letting the gratin rest after baking thickens the sauce for a perfect creamy texture.
  • If you prefer a less rich dish, substitute half-and-half for heavy cream.
  • Broiling is optional but recommended for a nicely browned top.

Find it online: https://dishcooks.com/au-gratin-potatoes-recipe/