This Leek Gratin Recipe is a classic baked side dish of tender leeks and chopped eggs layered under a creamy white cheddar cheese sauce and baked until golden and bubbling. It comes together in 40 minutes, and you can assemble it up to 24 hours ahead and bake it just before serving, making it easy and elegant enough for a holiday table, a dinner party, or a leisurely brunch.
If you love leeks, use them to make vichyssoise, a cold potato and leek soup.
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A Quick Look at Creamy Leek Gratin
✅ Recipe Name: Baked Leek Gratin Recipe
⏲️ Ready In: 40 minutes
🥣 Main Ingredients: Hard-boiled eggs, leeks, white cheddar, butter, paprika, Parmesan cheese
📖 Dietary Info: Vegetarian; can be easily gluten-free with one swap
♨️ Method: Stovetop to cook leeks and sauce and then bake in the oven
🍽️ Yield: 8-10 servings
⭐️ Difficulty: Easy enough for any level cook
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This one comes straight from my mom’s recipe box, and it’s still my favorite way to cook leeks. I often serve it at Thanksgiving, and the milder, slightly sweet flavor of the leeks cooked in butter never fails to win people over immediately.
The hard-boiled eggs are what make this dish unique; they add substance and make it hearty enough to serve as a light entrée with a green salad. I love that I can make it the day before and then slide it into the oven 30 minutes before mealtime. It’s one of those dishes that Great far more impressive than the effort it takes!
Since leeks are at their peak in spring, this dish makes an excellent addition to your Easter dinner menu.
Table of Contents
Why You Will Love This Recipe
- You can make it ahead. Assemble the whole cheesy leek bake up to 24 hours in advance, cover it, and refrigerate. Great for entertaining.
- It’s easy, yet impressive. About 30 minutes of hands-on cooking, start to finish, for a golden, bubbling dish that looks like it took far more time and energy than it did.
- It works as a side dish or a light entrée. Serve it alongside roast pork, turkey, or crusted rack of lamb, or enjoy as the centerpiece for brunch or lunch with a green salad.
- It’s a fresh take on a holiday classic. Sweet, mild leeks in a cheddar and Parmesan sauce make a welcome change from the traditional creamed pearl onions on the Thanksgiving table.
Ingredients
Here’s what you’ll need to create this crowd-pleasing dish (quantities are included in the recipe card below):
- Hard-boiled eggs: They add substance and a little richness, and turn a side dish into something hearty enough to serve as a light entrée. Peel them and cut each one into 8 pieces so they layer evenly across the bottom of the dish. See my tip below for how to hard-boil eggs two ways.
- Medium leeks: Leeks are in the same family as onions and shallots, but are milder and a bit sweeter, which is why I love them in this gratin dish.
- Whole milk: Use whole milk for the richest flavor and creamiest consistency.
- White cheddar cheese: I prefer using white cheddar to keep the color lighter in this dish. If you don’t mind a darker color, you can use yellow cheddar which tastes the same.
- Grated Parmesan cheese: Adds a salty, nutty depth that cheddar alone doesn’t have. Grate it fresh if you can because it melts more smoothly than the pre-grated kind.
- Cayenne pepper: Adds a subtle kick to the dish
TIP: How to hard boil eggs
In a large saucepan, cover eggs with water. Bring to a boil over high heat. Reduce heat to simmer and cook for 6 to 8 minutes (cook for 8 minutes if at higher altitude). Remove from heat and leave eggs in hot water for another 3 to 5 minutes.
Alternatively, pressure cook eggs in an Instant Pot for 5 to 8 minutes (lower time if eggs are at room temperature, longer time if cold). Drain and immediately place in ice water until cooled.
Variations
- Add a crunchy topping. Toss 1/2 cup panko or fresh breadcrumbs with a tablespoon of melted butter and scatter over the cheese before baking. This adds a crisp, golden crust, a nice contrast to the creamy sauce underneath, similar to this broccoli rice casserole recipe.
- Change up the cheese. Gruyère or Comté in place of the cheddar gives the sauce a nuttier, more French flavor. Fontina melts beautifully if you want it extra creamy.
- Make individual servings. Divide everything among six small gratin dishes or ramekins instead of one large dish. Lovely for a dinner party, and the baking time stays about the same. Watch them closely, as smaller dishes brown faster.
- Make it gluten-free. Use your favorite gluten-free flour blend in place of the all-purpose flour in the cheese sauce. Everything else stays the same.
For more easy side dish casseroles try these roasted carrot soufflé and fresh green bean casserole with cheese.
How To Make This Leek Au Gratin Recipe
Here are the steps involved in making this leek and egg gratin. To get started, preheat the oven to 450 degrees F.
- Place eggs in baking dish. Cut each hard-boiled egg into 8 pieces. Arrange them in a single layer in a 1 1/2- to 2-quart gratin or baking dish. You can also use a 10-inch pie pan.
- Prep leeks. Remove the dark green portion of the leeks and discard it. Cut off the root end and cut each leek in half lengthwise. Rinse well, making sure to remove all the dirt. Pat the leeks dry and coarsely chop them.
- Cook the leeks. In a large skillet, melt 4 tablespoons of butter over medium heat. Add the leeks and cook until tender, about 5-7 minutes.
- Add the leeks to the eggs. Spoon the cooked leeks over the top of the eggs in the gratin dish. Skip washing the skillet because you use it to make the cheese sauce.
- Melt the butter. Melt the remaining 2 tablespoons of butter over low heat in the same skillet.
- Add the flour. Whisk the flour into the melted butter until smooth.
- Make the roux. Cook the roux (flour and butter mixture) over low heat for 3 minutes, whisking constantly. This removes the raw flour taste from the mixture
- Add the milk. Slowly pour in warmed milk in a thin, steady stream while whisking constantly to prevent lumps. Continue cooking over low heat, stirring or whisking frequently, until the sauce is smooth, lump-free, and thick enough to coat the back of a spoon.
- Add the cheese and seasonings. Whisk in 1/4 cup of the Cheddar cheese, Parmesan cheese and cayenne pepper. Season to taste with salt and pepper.
- Finish assembling the dish. Pour the sauce evenly over the leeks and eggs. Sprinkle the top with the remaining 1/4 cup of Cheddar cheese.
- Bake and serve. Bake the leek gratin for 10 minutes or until bubbly and top is golden brown. Enjoy this leek casserole side dish with sliced roasted no-basted turkey.
Tips for Success
- Wash and dry leeks. Leeks hide a lot of dirt so washing them well is key. Make sure after rinsing, that you drain the leeks well before they go in the skillet.
- Don’t wash the skillet. Make the white cheddar cheese sauce in the same pan you cooked the leeks in. All that buttery leek flavor goes straight into the sauce.
- Cook the roux the full 3 minutes. It’s tempting to rush this, but those few minutes cook out the raw flour taste. Keep the heat low and whisk constantly so it doesn’t brown.
- Warm the milk before adding. Warm milk will incorporate faster and result in a smoother sauce.
- Grate the cheese yourself. Pre-shredded cheese is coated to keep it from clumping in the bag, and that coating can make a cheese sauce grainy.
Storage & Make Ahead
Make Ahead
- As a make ahead brunch side dish, assemble the gratin up to a day ahead, cover and refrigerate.
- Around 30-45 minutes before baking, remove gratin from the refrigerator and bring to room temperature before baking
Storage
- Cool the baked gratin, then cover it tightly or transfer to an airtight container. It keeps in the refrigerator for up to 3 days.
- I don’t recommend freezing this one. Hard-boiled egg whites turn rubbery and weep water once frozen and thawed, and cream sauces tend to separate.
Reheating
- The best method for reheating is the oven. Cover the dish with foil and reheat at 325°F for 15-20 minutes, until warmed through.
- Remove the foil for the last few minutes if you’d like the top to crisp back up.
- You can also reheat individual servings in the microwave in short bursts, stirring between each one.
Leek Gratin Recipe FAQs
Almost always because of moisture left in the leeks. Leeks trap a lot of water in their layers, so pat them thoroughly dry after rinsing, and cook them tender and most of the liquid has evaporated from the pan. A sauce that’s too thin going into the oven can also be the culprit. Make sure it’s thick enough to coat the back of a spoon before you pour it over.
Yes, for this recipe. Sautéing the leeks first softens them, concentrates their sweetness, and drives off the water that would otherwise thin the cheese sauce. It also builds the buttery base you’ll use to make the sauce in the same skillet. Raw leeks simply won’t turn tender in a 10-minute bake.
Lumpy white sauce (before adding the cheese) can result from using cold milk, adding the milk too quickly, or not whisking constantly as the sauce cooks. To fix it, remove the sauce from the heat and whisk vigorously until smooth. If lumps remain, strain the sauce through a fine-mesh sieve, then add the cheese and seasonings.
What to Serve With This Leek Gratin
I love to serve this leek gratin as a Thanksgiving side dish, in place of the traditional creamed onion dish. In addition to roast turkey, here are some other dishes to serve it with:
- As part of a brunch or lunch, with spiced bacon twists and spinach salad with lemon dressing.
- For dinner it makes a great side dish for roast pork loin, spiced pork tenderloin, or whole beef tenderloin in the oven.
More Delicious Side Dishes
Did you make this recipe?
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Baked Leek Gratin Recipe
Ingredients
- 8 hard boiled eggs, peeled
- 10 medium medium leeks
- 6 tablespoons butter, divided use
- 2 tablespoons all-purpose flour
- 1 ½ cups whole milk, warmed
- ½ cup shredded white Cheddar cheese, around 2 ounces, divided use
- ¼ cup grated Parmesan cheese
- ¼ teaspoon cayenne pepper
Instructions
- Preheat oven to 450 degrees F.
- Cut each egg into 8 pieces. Arrange in a single layer in a 1 1/2 to 2 quart gratin dish (or a 10-inch pie pan). Set aside.
- Remove dark green portion of leeks and throw away. Cut off the root end and cut each leek in half lengthwise. Rinse well, making sure to remove all the dirt. Pat dry. Coarsely chop leeks.
- In a large skillet, melt 4 tablespoons of the butter over medium heat. Add the leeks and cook until tender, about 5 to 7 minutes. Spoon the cooked leeks over the top of the eggs in the gratin dish – don’t wash the skillet!
- In the same skillet, melt the remaining 2 tablespoons of butter over low heat. Whisk the flour into the melted butter until smooth. Cook over low heat, whisking constantly, for 3 minutes. (This removes the raw flour taste from the mixture.)
- Slowly pour in warmed milk in a thin, steady stream while whisking constantly to prevent lumps. Continue cooking over low heat, stirring or whisking frequently, until the sauce is smooth, lump-free, and thick enough to coat the back of a spoon.
- Whisk in 1/4 cup of the Cheddar cheese, Parmesan cheese, and cayenne pepper. Season to taste with salt and pepper.
- Pour sauce evenly over the leeks and eggs.
- Sprinkle top with remaining 1/4 cup Cheddar cheese. Bake for 10 minutes or until bubbly and top is golden brown.
Notes
Nutrition
Nutrition information is automatically calculated, so should only be used as an approximation.
I loved it! I will enjoy trying other recipes of yours
Thank you, Lydia! I’m so happy you enjoyed our recipe.
I’ve been looking for a new way to eat leeks. I’m going to give this a try!
Great! Let us know what you think.
It’s my favorite for leeks!