Baked Leek Gratin is easy to prepare, full of flavor, and great to make year round. Hard boiled eggs and sweet, mild leeks are baked in a luscious creamy cheese sauce. Plus, it’s flexible and can be served as a side dish or light entrée. Make it after Easter to use up all those hard boiled eggs, or as a side dish at Thanksgiving instead of traditional creamed onions. It’s also perfect as part of a Mother’s Day brunch!

Table of Contents
  1. Leek Gratin Ingredients
  2. What is a Leek? What do leeks taste like?
  3. How To Cook Leeks Au Gratin
  4. Watch Video: How to make Leeks in Cheese Sauce
  5. What to serve with this Leek Gratin
  6. Can I make this baked Leek Side Dish ahead of time?
  7. How to store Baked Leeks with Cheese
  8. How to prepare Leeks FAQ
  9. Leek Gratin Recipe

Leek Gratin Ingredients

I love this Leek Gratin recipe, which is straight from mom’s recipe box. What’s not to love – it’s comprised of hard boiled eggs, leeks sautéed in butter and a creamy Parmesan-Cheddar cheese sauce. Yum!

What is a Leek? What do leeks taste like?

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.

Leeks vs Green Onions

Green onions and leeks look similar and they are, in fact in the same family – just different species. While both have an onion flavor, leeks are milder and a bit sweeter tasting than green onions. And leeks are fatter and longer.

How To Cook Leeks Au Gratin

Here are the steps involved in making this amazing side dish:

  1. Prep oven.
    Preheat oven to 450 degrees.
  2. Place eggs in baking dish.
    Cut each egg into 8 pieces. Arrange in a single layer in a 1 1/2 to 2 quart gratin or baking dish (or a 10-inch pie pan). Set aside.
  3. Prep leeks.
    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.
  4. Cook leeks.
    In a large skillet, melt 4 tablespoons of butter over medium heat. Add leeks and cook until tender, about 5 to 7 minutes.
  5. Add leeks to eggs.
    Spoon cooked leeks over the top of the eggs in the gratin dish – don’t wash the skillet.
  6. Make a cheese sauce.
    In the same skillet, melt remaining 2 tablespoons of butter over low heat. Whisk in flour and cook for 3 minutes, whisking constantly. Slowly begin to whisk in milk; increase heat to medium and cook sauce, whisking, until bubbly and thickened. Whisk in 1/4 cup of the Cheddar cheese, Parmesan cheese and cayenne pepper. Season to taste with salt and pepper.
  7. Add sauce and more cheese.
    Pour sauce evenly over the leeks and eggs. Sprinkle top with remaining 1/4 cup Cheddar cheese.
  8. Bake; serve.
    Bake for 10 minutes or until bubbly and top is golden brown.
Scoop of Leek Gratin in spoon hovering over casserole dish

Watch Video: How to make Leeks in Cheese Sauce

Watch this video to see how easy it is to prepare!

What to serve with this Leek Gratin

I love to serve this Leek Gratin on Thanksgiving – in place of the traditional creamed onion dish. In addition to roast turkey, here are some other dishes to serve it with:

Can I make this baked Leek Side Dish ahead of time?

Yes you can prepare the gratin earlier in the day, cover and refrigerate. Bring to room temperature, then pop it in the oven to bake just prior to serving.

How to store Baked Leeks with Cheese

If assembling the gratin ahead of time, cover and refrigerate. Bring to room temperature before baking.

How to prepare Leeks FAQ

How to cut Leeks

To chop leeks, first remove the dark green leaves and throw away. Next, cut off the root end, then cut in half lengthwise. Rinse well, making sure to remove all the dirt. Pat dry. Cut across the leek into slices, then chop the slices (it’s all in the video!).

How to clean Leeks

After removing the dark green leaves and root end, slice the leek in half lengthwise. Place under running water, gently fanning out the layers to get water inside and wash out any trapped dirt. Pat dry.

What part of the leek do you eat?

The white and light green portions are the best to eat; the dark green leaves can be tough and don’t have much flavor.

Print
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Scoop of Leek Gratin in spoon hovering over casserole dish

Leek Gratin Recipe

Baked Leek Gratin is easy to prepare, full of flavor, and great to make year round. Hard boiled eggs and sweet, mild leeks are baked in a luscious creamy cheese sauce. Plus, it’s flexible and can be served as a side dish or light entrée. Make it after Easter to use up all those hard boiled eggs, or as a side dish at Thanksgiving instead of traditional creamed onions. It’s also perfect as part of a Mother’s Day brunch!

  • Yield: 8 to 10 servings 1x

Ingredients

Scale
  • 8 hard boiled eggs, peeled
  • 10 medium leeks
  • 6 tablespoons butter, divided
  • 2 tablespoons all-purpose flour
  • 1 1/2 cups whole milk
  • 1/2 cup shredded white Cheddar cheese (around 2 ounces), divided
  • 1/4 cup grated Parmesan cheese
  • 1/4 teaspoon cayenne pepper

Instructions

  1. Preheat oven to 450 degrees.
  2. 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.
  3. 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.
  4. 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!
  5. In the same skillet, melt the remaining 2 tablespoons of butter over low heat. Whisk in the flour and cook for 3 minutes, whisking constantly. Slowly begin to whisk in the milk, increase the heat to medium and cook sauce, whisking, until bubbly and thickened. Whisk in 1/4 cup of the Cheddar cheese, Parmesan cheese and cayenne pepper. Season to taste with salt and pepper.
  6. Pour sauce evenly over the leeks and eggs.
  7. Sprinkle top with remaining 1/4 cup Cheddar cheese. Bake for 10 minutes or until bubbly and top is golden brown.

Notes

Make ahead: Gratin can be assembled but not baked up to 24 hours in advance, covered and stored in the refrigerator. Bring to room temperature before baking.

Gluten free: use gluten free flour blend.

  • Author: From “A Well-Seasoned Kitchen®” by Sally Clayton and Lee Clayton Roper
  • Category: side dish, breakfast and brunch main dish, gluten free
  • Method: Bake
  • Cuisine: French
Scoop of Leek Gratin in spoon hovering over casserole dish

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About the author

Hi, I'm Lee.

I am inspired by my mother, Sally’s, love of cooking and entertaining to gather friends and family together over great meals and conversation. In fact, I held my first dinner party at the age of 16. Throughout the years, I haves provided recipes, menu advice and cooking tips to friends seeking uncomplicated and delicious ideas for home entertaining.


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