Potato Leek Au Gratin – Creamy Three-Cheese Potato Casserole
If you’re looking for a rich, comforting side dish that’s perfect for holidays or special dinners, this Potato Leek Au Gratin is a delicious choice. Made with tender russet potatoes, buttery sautéed leeks, and three flavorful cheeses, this creamy baked casserole is the kind of dish that makes any meal feel special.
What makes this potato leek gratin stand out is its combination of Gruyère, blue cheese, and Parmesan. Gruyère adds a wonderfully nutty flavor, blue cheese brings a savory tang, and Parmesan helps create a beautifully golden topping. Together with whole milk and heavy cream, these cheeses form a rich sauce that coats every bite.
Fresh leeks give this recipe a delicate onion flavor without overpowering the potatoes. Slowly cooking the leeks in butter brings out their natural sweetness, while garlic, stone-ground mustard, and a touch of nutmeg add depth to the creamy sauce.
Unlike traditional potato gratins made with thinly sliced potatoes, this recipe uses ¾-inch cubes of russet potatoes. The cubes are layered with the creamy leek mixture, shredded cheeses, and fresh chives, creating a hearty casserole with wonderful texture.
To prepare the dish, sauté the sliced leeks in butter until tender. Add the milk, cream, blue cheese, garlic, mustard, and seasonings, then simmer gently until slightly thickened. Layer the potatoes, leek mixture, and remaining cheeses in a buttered baking dish.
A 9×13-inch ceramic baking dish is ideal for assembling and serving this casserole. Its generous size accommodates the layers while making an attractive presentation at the dinner table.
Bake covered at 400°F for 45 minutes, then uncover and continue baking for approximately 30 minutes, until the potatoes are fork-tender and the top is golden brown. Let the gratin rest for 15 minutes before serving.
This Potato Leek Au Gratin is especially delicious alongside roasted chicken, beef, pork, or lamb. It’s also a wonderful addition to Thanksgiving, Christmas, and other holiday menus.
With its creamy texture, tender potatoes, sweet leeks, and three-cheese topping, this comforting potato casserole is sure to become a favorite side dish.
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Potato Leek Au Gratin
- Total Time: 1:45
- Yield: 6-8
Ingredients
- 4 tbsp Butter
- 1 1/2 cups Whole milk
- 1 cup Heavy cream
- 3 Large garlic cloves finely chopped
- 1 tbsp Stone ground mustard
- 1/4 tsp Freshly grated nutmeg
- 3/4 tbsp Kosher salt
- 1 tsp Freshly ground pepper
- 2 oz Blue cheese
- 6 oz Grated gruyere cheese
- 2 oz Freshly grated parmesan cheese
- 3 lb Leek, white and light green portions, washed and sliced into 1/4 inch rings
- 2 lb Russet potatoes (3-4 medium), peeled and cubed into 3/4 inch pieces
- 3 tbsp Minced fresh chives
Instructions
- Position a rack in the center of the oven and heat the oven to 400°F. Grease a 9×13-inch baking dish or a large cast iron skillet with butter.
- In 12 inch nonstick skillet over medium heat, melt the butter. Add the leeks, stirring until leeks are completely coated. Cover and cook, stirring occasionally, until the leeks are tender, about 20 minutes. Add the milk, cream, blue cheese, garlic, mustard, nutmeg, salt and pepper and simmer uncovered. Stir the mixture occasionally, until slightly thickened, about 15 minutes. Be careful not to let boil. Remove from heat, and allow to cool.
- In a large bowl mix the gruyere and parmesan cheese.
- Layer one third of the potatoes in the baking dish or skillet. Pour one third of the leek mixture over the top. Sprinkle one third of grated cheese and 1 tbs of chives. Repeat to make two more layers reserving the last layer of chives.
- Cover Au Gratin with foil and bake for 45 minutes. Remove cover and continue baking until potatoes are completely tender when poked with fork and the crust is golden brown, about 30 more minutes. Allow to sit for 15 minutes after removing from oven. Garnish with reserved chives and serve.
- Prep Time: :30
- Cook Time: 1:15
- Category: Side Dish
- Method: Baking