Roasted Veggies

Roasted Leek And Potato Gratin

Name: Roasted Leek And Potato Gratin
Prep time: 30 min
Cook time: 40 min
Total time: 70 min
Yield: 6 servings
Ingredients: 2 large leeks, thinly sliced; 3-4 large potatoes, thinly sliced; 2 tablespoons unsalted butter; 1/2 cup grated Gruyère cheese; 1/2 cup grated Parmesan cheese; 1/4 cup heavy cream; 1 teaspoon kosher salt; 1/2 teaspoon black pepper; 2 cloves garlic, minced; 1/4 cup chopped fresh parsley

By Quinn Ainsworth · June 19, 2026 · Roasted Veggies

Prep30 min

Cook40 min

Total70 min

Serves6

I still remember the first time I tasted a roasted leek and potato gratin. It was at a family gathering, and my aunt had made it as a side dish. The combination of tender leeks, creamy potatoes, and a blend of cheeses was absolute perfection. From that day on, I was hooked. I started experimenting with different recipes, trying to recreate that magical flavor. And after many trials and errors, I finally landed on the perfect recipe.

This roasted leek and potato gratin is a game-changer. It's easy to make, yet impressive enough to serve at any dinner party. The best part? It's incredibly versatile. You can serve it as a side dish, or add some protein like chicken or bacon to make it a main course.

So, what makes this recipe so special? For starters, it's the combination of flavors. The sweetness of the leeks, the earthiness of the potatoes, and the creaminess of the cheese all come together to create a dish that's greater than the sum of its parts. And then there's the texture - the tender leeks, the crispy top, and the creamy potatoes all work together to create a dish that's both comforting and elegant.

I love making this recipe in the fall and winter, when the leeks and potatoes are at their peak season. It's the perfect side dish for a hearty roast dinner, or a comforting main course on a cold winter's night. And the best part? It's incredibly easy to make ahead of time, so you can prepare it in advance and simply pop it in the oven when you're ready.

In this recipe, I'll walk you through every step of the way, from preparing the leeks and potatoes to assembling the gratin and baking it to perfection. I'll also share some tips and tricks for getting the best results, and some variations you can try to make the recipe your own.

Why You’ll Love This Recipe

This recipe is incredibly easy to make ahead of time, so you can prepare it in advance and simply pop it in the oven when you're ready.
The combination of flavors and textures is absolute perfection, with tender leeks, creamy potatoes, and a blend of cheeses.
It's a versatile dish that can be served as a side or a main course, making it perfect for any occasion.
The recipe is easy to customize, so you can add your own favorite ingredients or spices to make it your own.
It's a great way to use up any leftover leeks or potatoes you have on hand, reducing food waste and saving you money.
The dish is perfect for a crowd, as it can be easily scaled up or down to feed any number of people.
It's a comforting and elegant dish that's sure to impress your family and friends.

Why This Recipe Works

The key to a great roasted leek and potato gratin is in the layering. You want to create a dish that's both visually appealing and texturally interesting. That's why I start by slicing the leeks and potatoes into thin rounds. This helps them cook evenly and creates a beautiful, layered effect in the finished dish.

Another important factor is the cheese. I use a combination of Gruyère and Parmesan, which provides a rich, creamy flavor and a nice balance of textures. The Gruyère adds a nutty, slightly sweet flavor, while the Parmesan provides a salty, umami taste.

Finally, there's the cooking method. I use a combination of roasting and baking to get the best results. The leeks and potatoes are roasted in the oven until they're tender and lightly caramelized, then they're topped with a creamy cheese sauce and baked until golden and bubbly.

The result is a dish that's both comforting and elegant, perfect for any occasion. Whether you're serving it as a side dish or a main course, this roasted leek and potato gratin is sure to impress.

Ingredients You’ll Need

When it comes to making a great roasted leek and potato gratin, the ingredients are key. You'll need a few basic ingredients, including leeks, potatoes, cheese, and cream. Look for leeks that are firm and have a nice, bright green color, and choose potatoes that are high in starch, like Russet or Idaho. For the cheese, I recommend using a combination of Gruyère and Parmesan, which provides a rich, creamy flavor and a nice balance of textures.

Here are the ingredients you'll need to make this recipe:

2 large leeks, thinly slicedLook for leeks that are firm and have a nice, bright green color. You can also use smaller leeks, just adjust the cooking time accordingly.
3-4 large potatoes, thinly slicedChoose potatoes that are high in starch, like Russet or Idaho. This will help them cook evenly and give them a nice, fluffy texture.
2 tablespoons unsalted butterUse high-quality, European-style butter for the best flavor. You can also use salted butter, just omit the extra salt called for in the recipe.
1/2 cup grated Gruyère cheeseGruyère has a nutty, slightly sweet flavor that pairs perfectly with the leeks and potatoes. You can also use other cheeses, like Cheddar or Parmesan, but Gruyère is my favorite.
1/2 cup grated Parmesan cheeseParmesan adds a salty, umami flavor to the dish. You can also use other hard cheeses, like Asiago or Pecorino.
1/4 cup heavy creamHeavy cream adds a rich, creamy texture to the dish. You can also use half-and-half or whole milk, but heavy cream is my favorite.
1 teaspoon kosher saltKosher salt has a milder flavor than table salt, which makes it perfect for cooking. You can also use other types of salt, like sea salt or Himalayan pink salt.
1/2 teaspoon black pepperFreshly ground black pepper adds a nice, peppery flavor to the dish. You can also use white pepper, but black pepper is my favorite.
2 cloves garlic, mincedGarlic adds a nice, savory flavor to the dish. You can also use shallots or onions, but garlic is my favorite.
1/4 cup chopped fresh parsleyParsley adds a fresh, herbaceous flavor to the dish. You can also use other herbs, like thyme or rosemary, but parsley is my favorite.

Ingredients for Roasted Leek And Potato Gratin

Equipment You’ll Need

Large bowlMandoline or sharp knifeCutting boardRoasting panInstant-read thermometerWhiskMeasuring cups and spoons

How to Make Roasted Leek And Potato Gratin

1
Preheat your oven to 400°F (200°C). While the oven is heating up, slice the leeks and potatoes into thin rounds. You can use a mandoline or a sharp knife to get the job done.
2
In a large bowl, combine the sliced leeks and potatoes. Drizzle with 1 tablespoon of the unsalted butter and toss to coat. Season with salt and pepper to taste.
3
Spread the leek and potato mixture out in a single layer on a roasting pan. Roast in the preheated oven for 20-25 minutes, or until the leeks and potatoes are tender and lightly caramelized.
4
While the leeks and potatoes are roasting, prepare the cheese sauce. In a small saucepan, melt the remaining 1 tablespoon of unsalted butter over medium heat. Add the minced garlic and cook for 1-2 minutes, or until fragrant.
5
Add the heavy cream to the saucepan and bring to a simmer. Let cook for 2-3 minutes, or until the cream has reduced slightly and the sauce has thickened. Remove from heat and stir in the grated Gruyère and Parmesan cheese. Season with salt and pepper to taste.
6
Once the leeks and potatoes are done roasting, remove them from the oven and let them cool slightly. In a large bowl, combine the roasted leek and potato mixture, the cheese sauce, and the chopped fresh parsley. Toss to coat, making sure the leeks and potatoes are evenly coated with the cheese sauce.
7
Transfer the leek and potato mixture to a baking dish and top with additional grated cheese if desired. Bake in the preheated oven for 15-20 minutes, or until the top is golden and bubbly.
8
Remove the gratin from the oven and let it cool for a few minutes before serving. Serve hot, garnished with additional parsley if desired.
9
To get the best results, make sure to not overcrowd the roasting pan. This will help the leeks and potatoes cook evenly and prevent them from steaming instead of roasting.
10
Also, don't overmix the leek and potato mixture with the cheese sauce. You want to maintain the texture of the leeks and potatoes, so mix just until they're evenly coated.
11
Finally, let the gratin rest for a few minutes before serving. This will help the cheese set and the flavors meld together, making the dish even more delicious.

Expert Tips

To get the best results, use high-quality ingredients, including fresh leeks and potatoes, and good-quality cheese.
Don't overcrowd the roasting pan, as this can prevent the leeks and potatoes from cooking evenly.
Let the gratin rest for a few minutes before serving, as this will help the cheese set and the flavors meld together.
You can also make this recipe ahead of time and refrigerate or freeze it until you're ready to bake it.
To add some extra flavor to the dish, try adding some diced ham or bacon to the leek and potato mixture.
You can also use different types of cheese, such as Cheddar or Parmesan, to change up the flavor of the dish.
Finally, don't be afraid to experiment with different herbs and spices to add some extra flavor to the dish.

Common Mistakes to Avoid

Overcrowding the roasting pan, which can prevent the leeks and potatoes from cooking evenly.
Not letting the gratin rest before serving, which can cause the cheese to be runny and the flavors to not meld together.
Using low-quality ingredients, which can affect the flavor and texture of the dish.
Not cooking the leeks and potatoes long enough, which can cause them to be undercooked and crunchy.
Adding too much cheese, which can make the dish overly rich and heavy.
Not stirring the cheese sauce enough, which can cause it to be lumpy and uneven.

Variations and Substitutions

Try adding some diced ham or bacon to the leek and potato mixture for added flavor.
Use different types of cheese, such as Cheddar or Parmesan, to change up the flavor of the dish.
Add some diced onions or shallots to the leek and potato mixture for added flavor.
Use fresh herbs, such as thyme or rosemary, to add some extra flavor to the dish.
Try using different types of potatoes, such as sweet potatoes or Yukon golds, to change up the flavor and texture of the dish.
Add some grated nutmeg or cayenne pepper to the cheese sauce for added depth of flavor.
Use a combination of heavy cream and milk to make the cheese sauce, for a lighter and more dairy-free option.

What to Serve With Roasted Leek And Potato Gratin

This roasted leek and potato gratin is perfect as a side dish or main course. You can serve it with a variety of dishes, such as roasted chicken or beef, or as a vegetarian main course. It's also a great option for a dinner party or special occasion.

Some other ideas for serving this dish include:

Roasted chicken or beefGrilled steak or salmonVegetarian main courseDinner party or special occasionHoliday mealWeeknight dinner

Make-Ahead, Storage, Freezing and Reheating

This roasted leek and potato gratin can be made ahead of time and refrigerated or frozen until you're ready to bake it. To refrigerate, simply assemble the gratin and store it in the refrigerator for up to 24 hours. To freeze, assemble the gratin and store it in the freezer for up to 3 months. When you're ready to bake it, simply thaw it overnight in the refrigerator and bake as directed.

To reheat the gratin, simply bake it in the oven at 350°F (180°C) for 15-20 minutes, or until it's hot and bubbly. You can also reheat it in the microwave, but be careful not to overheat it.

It's also a good idea to let the gratin rest for a few minutes before serving, as this will help the cheese set and the flavors meld together. You can serve it hot, garnished with additional parsley if desired.

Frequently Asked Questions

What type of potatoes should I use for this recipe?

You can use any type of potato you like, but high-starch potatoes like Russet or Idaho work best. They will yield a lighter, fluffier texture.

Can I make this recipe ahead of time?

Yes, you can make this recipe ahead of time and refrigerate or freeze it until you're ready to bake it. Simply assemble the gratin and store it in the refrigerator for up to 24 hours or freeze it for up to 3 months.

What type of cheese should I use for this recipe?

You can use any type of cheese you like, but a combination of Gruyère and Parmesan works best. The Gruyère adds a nutty, slightly sweet flavor, while the Parmesan provides a salty, umami taste.

Can I use fresh herbs instead of dried herbs?

Yes, you can use fresh herbs instead of dried herbs. Simply chop the fresh herbs and add them to the recipe as directed.

How do I prevent the gratin from becoming too brown or burnt?

To prevent the gratin from becoming too brown or burnt, make sure to not overcrowd the roasting pan and to stir the cheese sauce regularly. You can also cover the gratin with foil if it starts to get too brown.

Can I make this recipe in a slow cooker?

Yes, you can make this recipe in a slow cooker. Simply assemble the gratin and cook it on low for 2-3 hours or on high for 1-2 hours.

What is the best way to reheat the gratin?

The best way to reheat the gratin is to bake it in the oven at 350°F (180°C) for 15-20 minutes, or until it's hot and bubbly. You can also reheat it in the microwave, but be careful not to overheat it.

Can I freeze the gratin after it's been baked?

Yes, you can freeze the gratin after it's been baked. Simply let it cool completely, then wrap it tightly in plastic wrap or aluminum foil and freeze for up to 3 months. When you're ready to reheat it, simply thaw it overnight in the refrigerator and bake in the oven at 350°F (180°C) for 15-20 minutes, or until it's hot and bubbly.

The Full Recipe

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