Cheesy Potato Gratin Casserole Ultimate
This Cheesy Potato Gratin Casserole is a comforting and elegant dish perfect as a side for holidays or weeknight dinners. Layers of thinly sliced potatoes are baked in a creamy, cheesy sauce until golden and bubbly.
Equipment
- 9x13 inch baking dish
- Oven
- Mixing Bowls
- saucepan
- Whisk
- Measuring cups and spoons
- Mandoline slicer or knife
- Paper towels
- Aluminum foil
- Grater
Ingredients
- 2.5 lbs Yukon Gold or Russet potatoes, peeled and thinly sliced
- 2 cups heavy cream
- 1 cup milk
- 3 cloves garlic, minced
- 1.5 cups Gruyere cheese, shredded
- 1 cup sharp cheddar cheese, shredded
- 2 tablespoons unsalted butter
- 2 tablespoons all-purpose flour
- ¼ teaspoon nutmeg, freshly grated
- ½ teaspoon dried thyme
- 1 teaspoon salt, or to taste
- ½ teaspoon black pepper, or to taste
- 2 tablespoons fresh parsley, chopped for garnish
Instructions
- Preheat your oven to 375°F (190°C). Grease a 9x13 inch baking dish.
- Peel and thinly slice the potatoes (about 1/8 inch thick). Place the potato slices in a bowl of cold water to prevent them from browning.
- Drain the potatoes thoroughly and pat them dry with paper towels.
- In a saucepan, melt the butter over medium heat. Whisk in the flour and cook for 1-2 minutes, creating a roux.
- Gradually whisk in the milk and heavy cream, ensuring there are no lumps.
- Bring the mixture to a simmer, stirring constantly. Reduce the heat to low and cook for 5 minutes, or until slightly thickened.
- Remove from heat and stir in the minced garlic, nutmeg, thyme, salt, and pepper.
- Add the Gruyere and half of the cheddar cheese. Stir until the cheese is melted and the sauce is smooth and creamy. Taste and adjust seasonings as needed.
- Arrange a layer of potato slices in the prepared baking dish, slightly overlapping each slice.
- Pour a third of the cheese sauce over the potatoes, ensuring they are evenly coated.
- Repeat with another layer of potatoes and sauce.
- Top with the remaining potato slices and pour the remaining cheese sauce over the top.
- Sprinkle the remaining cheddar cheese evenly over the gratin.
- Cover the baking dish with aluminum foil and bake for 30 minutes.
- Remove the foil and bake for an additional 20-30 minutes, or until the potatoes are tender and the top is golden brown and bubbly. A knife inserted into the center should easily pierce the potatoes.
- Let the gratin rest for 10-15 minutes before serving. This allows the sauce to thicken slightly.
- Garnish with fresh parsley before serving.
Notes
For a spicier gratin, add a pinch of cayenne pepper or a dash of hot sauce to the cheese sauce. Smoked paprika can also be added for a smoky flavor. To add more vegetables, layer in some sautéed onions, mushrooms, or spinach between the potato layers. Leeks also add a wonderful savory flavor. For a lighter version, substitute some of the heavy cream with milk or vegetable broth. To make this gratin vegan, substitute the heavy cream and milk with full-fat coconut milk or a plant-based cream alternative and use a vegan cheese alternative.