Description
This classic Au Gratin Potatoes recipe features thinly sliced russet potatoes layered with a rich, creamy sauce made from caramelized onions, fresh garlic, thyme, and a blend of Gruyere and Parmesan cheeses. Baked to golden perfection, it’s a comforting and elegant side dish perfect for any special occasion or cozy family dinner.
Ingredients
Scale
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 & Fats
- 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
- Preheat Oven: Preheat your oven to 350°F to prepare for baking the potatoes. Alternatively, you can do this later after caramelizing the onions.
- Prepare Cream Mixture: Combine the heavy cream and milk in a medium measuring cup and microwave for 1 minute to temper the mixture. Set aside.
- Caramelize Onions: In a soup pot over medium heat, melt the butter and add the diced onions. Soften them for about 10 minutes, stirring often. Reduce heat to medium-low and continue cooking for another 10-15 minutes, stirring frequently until onions begin to brown and caramelize. Then add minced garlic and fresh thyme and cook for 2 more minutes.
- Create Cheese Sauce: Turn off the heat and let the pot cool for 1 minute. Gradually stir in the warm cream and milk mixture. Turn heat back to medium-high and bring to a gentle boil, then remove from heat. Slowly add the shredded Gruyere and Parmesan cheese, stirring as you add to allow the cheese to melt smoothly. Finally, season the sauce with salt and pepper.
- Slice Potatoes: Using a mandoline or a very sharp knife, slice the potatoes into 1/8-inch thick slices to ensure even cooking.
- Layer Ingredients: Lightly grease a 2.5-quart baking dish or a 9 x 13-inch dish. Arrange one-third of the potato slices evenly on the bottom. Lightly sprinkle with salt. Pour one-third of the cheese sauce over the potatoes. Repeat two more times with remaining potatoes and sauce, finishing with a layer of sauce on top.
- Bake Covered: Cover the baking dish tightly and bake in the preheated oven for 1 hour.
- Bake Uncovered & Optional Broil: Remove the cover and bake for an additional 30 minutes to brown the top. For extra color and a golden crust, broil at 425°F for 1-2 minutes, watching carefully to avoid burning.
- Rest and Serve: Remove the dish from the oven and let it rest for 5-10 minutes to allow the sauce to thicken. Garnish with chopped chives before serving.
Notes
- Use a mandoline slicer to achieve uniform potato slices for even cooking.
- Adjust the salt to taste, especially if using salted butter or cheeses with varying saltiness.
- Broiling is optional but adds a nice crispy top layer; watch closely to prevent burning.
- Letting the dish rest before serving helps the sauce thicken and improves texture.
- This dish pairs beautifully with roasted meats or fresh green salads for a complete meal.
- Prep Time: 20 minutes
- Cook Time: 1 hour 30 minutes
- Category: Side Dish
- Method: Baking
- Cuisine: French
Keywords: Au Gratin Potatoes, Potato gratin, Gruyere cheese, creamy potato bake, French side dish, comfort food
