Roast & Bake

Chicken And Leek Gratin

Name: Chicken And Leek Gratin
Prep time: 20 min
Cook time: 30 min
Total time: 50 min
Yield: 6 servings
Ingredients: 1.5 lbs (680g) chicken thighs, boneless; 2 large leeks, cleaned and sliced; 2 tbsp (30g) unsalted butter; 1/2 cup (120g) all-purpose flour; 1 cup (240ml) heavy cream; 1/2 cup (120g) grated Gruyère cheese; 1/4 cup (60g) grated Parmesan cheese; 2 cloves garlic, minced; 1 tsp (5g) dried thyme; 1/2 tsp (2g) salt; 1/4 tsp (1g) black pepper

By Delia Ingram · June 19, 2026 · Roast & Bake

Prep20 min

Cook30 min

Total50 min

Serves6

There's something special about a warm, comforting casserole that brings everyone together. For me, Chicken And Leek Gratin is more than just a recipe - it's a family tradition that never fails to put smiles on our faces. The combination of tender chicken, sweet caramelized leeks, and a rich, creamy sauce is absolute perfection.

I still remember the first time I made this dish for my family. It was a chilly winter evening, and we were all craving something hearty and comforting. I had all the ingredients on hand, so I decided to give it a try. The result was love at first bite - the flavors melded together beautifully, and the texture was just right.

Since then, Chicken And Leek Gratin has become a staple in our household. We make it for special occasions, like holidays and birthdays, but also for casual weeknight dinners. It's one of those dishes that never gets old, and everyone always asks for seconds.

What I love most about this recipe is its simplicity. The ingredients are easy to find, and the instructions are straightforward. It's also very versatile - you can serve it with a variety of sides, from mashed potatoes to roasted vegetables. And the best part? It's perfect for a crowd, so you can easily double or triple the recipe if you need to feed a larger group.

In this recipe, I'll guide you through the process of making Chicken And Leek Gratin from scratch. We'll start with the basics - selecting the right ingredients and preparing the leeks and chicken. Then, we'll move on to the cooking process, where we'll caramelize the leeks, cook the chicken, and assemble the gratin. Finally, we'll finish it off with a rich, creamy sauce and a golden-brown topping.

Why You’ll Love This Recipe

This recipe is perfect for a weeknight dinner, as it's easy to make and can be ready in under an hour.
The combination of chicken, leeks, and creamy sauce is a match made in heaven.
You can customize the recipe to your taste by adding your favorite herbs and spices.
It's a great way to use up leftover chicken and leeks, reducing food waste and saving you money.
The dish is perfect for a crowd, as it can be easily doubled or tripled to feed a larger group.
The leftovers are just as delicious as the first serving, making it a great option for meal prep.

Why This Recipe Works

The key to a great Chicken And Leek Gratin is in the layers of flavor. First, you have the caramelized leeks, which add a deep, sweet flavor to the dish. Then, you have the chicken, which is cooked to perfection and adds plenty of moisture to the gratin. Finally, you have the sauce, which brings everything together and adds a rich, creamy texture.

Another important aspect of this recipe is the cooking technique. By cooking the chicken and leeks separately before assembling the gratin, you can ensure that each component is cooked to perfection. This also helps to prevent the chicken from drying out and the leeks from becoming mushy.

The type of cheese you use is also crucial. I recommend using a combination of Gruyère and Parmesan, which provides a nice balance of flavors and textures. The Gruyère adds a rich, creamy flavor, while the Parmesan adds a nice salty kick.

Finally, the resting time is essential. By letting the gratin rest for a few minutes before serving, you can allow the flavors to meld together and the sauce to thicken. This makes a big difference in the overall texture and flavor of the dish.

Ingredients You’ll Need

When it comes to ingredients, the key to a great Chicken And Leek Gratin is to use high-quality components. Look for fresh, tender leeks and boneless, skinless chicken breasts. You'll also need a variety of cheeses, including Gruyère and Parmesan, as well as some heavy cream and butter. Don't forget to pick up some fresh thyme and rosemary, which add a nice herbal flavor to the dish.

One of the best things about this recipe is that it's relatively inexpensive. You can find all of the ingredients at your local grocery store, and they won't break the bank. Plus, the dish is perfect for using up leftover chicken and leeks, reducing food waste and saving you money.

1.5 lbs (680g) chicken thighs, bonelessI recommend using boneless, skinless chicken thighs for this recipe, as they are tender and have plenty of flavor. You can also use chicken breasts if you prefer, but thighs work better for this dish.
2 large leeks, cleaned and slicedLook for fresh, tender leeks with a nice white and green color. Make sure to clean them well before slicing, as they can be quite dirty.
2 tbsp (30g) unsalted butterI recommend using high-quality, unsalted butter for this recipe, as it adds a rich, creamy flavor to the dish. You can also use salted butter if you prefer, but unsalted works better for this recipe.
1/2 cup (120g) all-purpose flourAll-purpose flour is a must-have for this recipe, as it helps to thicken the sauce and add structure to the gratin. Make sure to use a high-quality flour that is fresh and has not been sitting on the shelf for too long.
1 cup (240ml) heavy creamHeavy cream is essential for this recipe, as it adds a rich, creamy texture to the sauce. You can also use half-and-half or whole milk if you prefer, but heavy cream works best for this dish.
1/2 cup (120g) grated Gruyère cheeseGruyère cheese is a must-have for this recipe, as it adds a rich, creamy flavor to the dish. You can also use other types of cheese, such as Parmesan or Cheddar, but Gruyère works best for this recipe.
1/4 cup (60g) grated Parmesan cheeseParmesan cheese is a nice addition to this recipe, as it adds a salty, nutty flavor to the dish. You can also use other types of cheese, such as Asiago or Romano, but Parmesan works well for this recipe.
2 cloves garlic, mincedGarlic is a must-have for this recipe, as it adds a nice depth of flavor to the dish. Make sure to mince it well before adding it to the recipe, as this helps to bring out the flavor.
1 tsp (5g) dried thymeDried thyme is a nice addition to this recipe, as it adds a nice herbal flavor to the dish. You can also use fresh thyme if you prefer, but dried thyme works well for this recipe.
1/2 tsp (2g) saltSalt is essential for this recipe, as it helps to bring out the flavors of the other ingredients. Make sure to use a high-quality salt that is fresh and has not been sitting on the shelf for too long.
1/4 tsp (1g) black pepperBlack pepper is a nice addition to this recipe, as it adds a nice depth of flavor to the dish. Make sure to use a high-quality pepper that is fresh and has not been sitting on the shelf for too long.

Equipment You’ll Need

Large heavy skillet or wokSharp chef's knifeInstant-read thermometerCutting boardMeasuring cups and spoonsWhisk9x13 inch baking dish

How to Make Chicken And Leek Gratin

1
Preheat your oven to 375°F (190°C).
2
In a large skillet, melt 1 tablespoon of butter over medium heat. Add the sliced leeks and cook, stirring occasionally, until they are tender and lightly browned, about 10-12 minutes.
3
Add the minced garlic to the skillet and cook for 1-2 minutes, until fragrant.
4
Add the chicken to the skillet and cook, stirring occasionally, until it is browned on all sides and cooked through, about 5-7 minutes.
5
In a separate saucepan, melt the remaining 1 tablespoon of butter over medium heat. Add the flour and cook, stirring constantly, for 1-2 minutes, until the mixture is lightly browned and has a nutty aroma.
6
Slowly pour in the heavy cream, whisking constantly, until the sauce is smooth and creamy.
7
Bring the sauce to a simmer and cook, stirring occasionally, until it has thickened and reduced slightly, about 5-7 minutes.
8
Stir in the grated Gruyère and Parmesan cheese until melted and smooth.
9
In a large bowl, combine the cooked chicken, leeks, and sauce. Season with salt, pepper, and thyme.
10
Transfer the mixture to a 9x13 inch baking dish and top with additional grated cheese.
11
Bake the gratin in the preheated oven for 25-30 minutes, until the top is golden brown and the sauce is bubbly.
12
Remove the gratin from the oven and let it rest for 10-15 minutes before serving.
13
Use an instant-read thermometer to check the internal temperature of the chicken, which should reach 165°F (74°C) in the thickest part of the breast.

Expert Tips

Make sure to cook the leeks slowly and patiently, as this helps to bring out their natural sweetness.
Don't overcook the chicken, as this can make it dry and tough.
Use high-quality cheese for the best flavor.
Let the gratin rest for at least 10-15 minutes before serving, as this helps the flavors to meld together.
You can customize the recipe to your taste by adding your favorite herbs and spices.
The leftovers are just as delicious as the first serving, making it a great option for meal prep.
You can also make the gratin ahead of time and refrigerate or freeze it for later use.

Common Mistakes to Avoid

Not cooking the leeks slowly and patiently, which can make them bitter and tough.
Overcooking the chicken, which can make it dry and tough.
Not using high-quality cheese, which can affect the flavor of the dish.
Not letting the gratin rest for at least 10-15 minutes before serving, which can make the flavors seem disjointed.
Not using an instant-read thermometer to check the internal temperature of the chicken, which can lead to undercooked or overcooked chicken.
Not whisking the sauce constantly, which can make it lumpy and uneven.

Variations and Substitutions

Add some diced ham or bacon to the gratin for added smokiness.
Use different types of cheese, such as Cheddar or Asiago, for a unique flavor.
Add some fresh herbs, such as parsley or rosemary, for added flavor.
Use leftover roasted chicken or turkey for a delicious and easy meal.
Add some sautéed mushrooms or spinach to the gratin for added flavor and nutrition.
Use gluten-free flour for a gluten-free version of the recipe.
Add some diced bell peppers or zucchini to the gratin for added flavor and nutrition.

What to Serve With Chicken And Leek Gratin

Chicken And Leek Gratin is a delicious and satisfying main dish that can be served with a variety of sides. Some of my favorite options include roasted vegetables, such as asparagus or Brussels sprouts, or a simple green salad with a light vinaigrette. You can also serve it with some crusty bread or over mashed potatoes for a hearty and comforting meal.

One of the best things about this recipe is that it's perfect for a crowd. You can easily double or triple the recipe to feed a larger group, and it's sure to be a hit. Just make sure to adjust the cooking time accordingly, and you'll have a delicious and satisfying meal that everyone will love.

Roasted vegetables, such as asparagus or Brussels sproutsA simple green salad with a light vinaigretteCrusty bread or over mashed potatoesA side of quinoa or riceSteamed broccoli or green beansA fruit salad or sorbet for dessert

Make-Ahead, Storage, Freezing and Reheating

Chicken And Leek Gratin can be stored in the refrigerator for up to 3 days or frozen for up to 2 months. To refrigerate, let the gratin cool completely, then cover it with plastic wrap or aluminum foil and refrigerate. To freeze, let the gratin cool completely, then transfer it to a freezer-safe container or bag and freeze.

To reheat, simply thaw the gratin overnight in the refrigerator, then bake it in the oven at 350°F (180°C) for 20-25 minutes, until the top is golden brown and the sauce is bubbly. You can also reheat it in the microwave, but be careful not to overheat, as this can make the sauce separate and the chicken dry out.

One of the best things about this recipe is that it's perfect for meal prep. You can make the gratin ahead of time, then refrigerate or freeze it for later use. This is a great option for busy weeknights or for a quick and easy lunch. Just make sure to label and date the container, and you'll have a delicious and satisfying meal ready to go.

In addition to refrigerating or freezing, you can also make the gratin ahead of time and store it in the refrigerator or freezer. This is a great option if you want to make the gratin for a special occasion or event. Simply assemble the gratin, then cover it with plastic wrap or aluminum foil and refrigerate or freeze until you're ready to bake it.

Frequently Asked Questions

What type of cheese is best for this recipe?

I recommend using a combination of Gruyère and Parmesan cheese for this recipe. The Gruyère adds a rich, creamy flavor, while the Parmesan adds a nice salty kick.

Can I use leftover chicken for this recipe?

Yes, you can use leftover chicken for this recipe. Simply shred or chop the chicken and add it to the gratin. This is a great way to use up leftover chicken and make a delicious and easy meal.

How do I prevent the sauce from separating?

To prevent the sauce from separating, make sure to whisk it constantly as you add the cream and cheese. You can also add a little bit of flour or cornstarch to the sauce to help thicken it and prevent separation.

Can I make this recipe ahead of time?

Yes, you can make this recipe ahead of time. Simply assemble the gratin, then cover it with plastic wrap or aluminum foil and refrigerate or freeze until you're ready to bake it.

How do I reheat the gratin?

To reheat the gratin, simply thaw it overnight in the refrigerator, then bake it in the oven at 350°F (180°C) for 20-25 minutes, until the top is golden brown and the sauce is bubbly. You can also reheat it in the microwave, but be careful not to overheat, as this can make the sauce separate and the chicken dry out.

Can I freeze the gratin?

Yes, you can freeze the gratin. Simply assemble the gratin, then transfer it to a freezer-safe container or bag and freeze. When you're ready to bake it, simply thaw it overnight in the refrigerator, then bake it in the oven at 350°F (180°C) for 20-25 minutes, until the top is golden brown and the sauce is bubbly.

How do I prevent the gratin from drying out?

To prevent the gratin from drying out, make sure to cover it with foil or plastic wrap during baking. You can also add a little bit of cream or cheese to the sauce to help keep it moist and creamy.

Can I make this recipe gluten-free?

Yes, you can make this recipe gluten-free. Simply use gluten-free flour instead of all-purpose flour, and make sure to check the ingredients of the cheese and cream to ensure they are gluten-free.

The Full Recipe

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