Skip to Content
March 30, 2024

Potato Leek Au Gratin

Hot out of the oven, we love a bubbling potato leek au gratin with plenty of Gruyére and blue cheese. Scoop up a serving at your next celebratory meal.

Categories

potato leek au gratin made with gruyère, parmesan, blue cheese, butter, cream, spices and ground mustard topped with chives
Photography by Gayle McLeod

Potatoes, every way we love em:

A Leek Potato Recipe To Fall For

Potatoes, leeks sauteed in butter, three kinds of cheese. Whole milk and heavy cream. It’s a fool-proof recipe for happy faces at the dinner table. Julia Child said “if you’re afraid of butter, use cream” and this over-the-top take on potatoes au gratin with Gruyére wholeheartedly embraces that spirit. We’ve got other great potato dishes lined up for you in our Potatoes au Gratin, Scalloped potatoes, and more in our Thanksgiving Roundup.

potato leek au gratin made with gruyère, parmesan, blue cheese, butter, cream, spices and ground mustard topped with chives

What Makes Potatoes “Au Gratin”?

Essentially, an “au gratin”—classically made with potatoes—is a dish that is covered with a layer of crusty, bubbly cheese. It’s a glamorous potato leek casserole brimming with butter and cream, these festively decadent leek-studded potatoes au gratin with plenty of Gruyére and blue cheese are your new favorite side. Potato and leek dauphinoise—while similarly a baked, creamy dish of sliced potatoes and leeks with a bubbling, browned crust—is differentiated from a potato gratin by the fact that potato dauphinoise is always made without cheese. Serve them with Kale Salad, Roast Turkey, Brussels Sprouts Gratin, Grated Beet Salad, Broccolini au Gratin, and Sweet Potato Casserole at your feast!

potato, leeks, Gruyère, parmesan, blue cheese, butter, cream, spices and ground mustard in prep bowls

Ingredients For This Potato And Leek Recipe

  • Heavy cream, whole milk, and salted butter

  • 3 pounds leeks and 2 pounds russet potatoes

  • Cheese: Crumbled blue cheese, grated parmesan cheese, grated gruyere cheese

  • Garlic cloves, stone ground mustard, grated nutmeg, kosher salt, freshly ground black pepper

cream being poured into a skillet with leeks, butter, milk, blue cheese, garlic, mustard, nutmeg, salt, and pepper.
leeks, butter, milk, cream, blue cheese, garlic, mustard, nutmeg, salt, and pepper being stirred in a skillet
potatoes, leek cream sauce, cheese and chives being layered in a baking dish
potatoes, leek cream sauce, cheese and chives layered in a baking dish

How Do You Make Leek And Potato Gratin?

  1. Preheat the oven to 400°F.

  2. Grease your pan. A 9x13-inch baking dish or a large cast iron skillet with butter will work.

  3. Cook the leeks in butter in a large nonstick skillet over medium heat. Add the milk, cream, blue cheese, garlic, mustard, nutmeg, salt, and pepper and cook until slightly thickened.

  4. Combine the gruyere and parmesan cheese in a big bowl.

  5. Layer your ingredients in your baking dish, starting with ⅓ of the potatoes, then pour ⅓ of the leek mixture over top. Evenly sprinkle with ⅓ of the cheese mixture and 1 tablespoon of the chives. Repeat with the remaining ingredients.

  6. Cover with foil and bake for 45 minutes.

  7. Uncover and bake until the potatoes are fork-tender and the crust is golden brown, about 30 minutes more.

  8. Sprinkle with chives and serve.

a baking dish of potato leek au gratin covered in foil ready to go in the oven
potato leek au gratin made with gruyère, parmesan, blue cheese, butter, cream, spices and ground mustard

How to Store Leftovers + Tips

  • Make ahead! This leek and potato gratin is the ideal make-ahead dish, and we know those words are music to your ears. You can easily assemble this recipe 48 hours ahead of time.

  • Wash your leeks after you prep them. Leeks can trap a little grit in between their fine layers, so give them a good rinse under running water after you’ve chopped them to be sure they’re totally clean.

  • On Gruyére: A Swiss cheese can only be labeled “Gruyére” if it is made in that region of Switzerland. Because it is aged for at least a year and then imported, it can be a bit more expensive than other Swiss cheese you might find. We think its distinctive rich, nutty flavor is worth the splurge, but you can substitute a less expensive Swiss cheese and your guests will be none the wiser.

  • Selecting a blue cheese. Most any blue will work for this, but be aware that some are much more pungent than others. We like a relatively mild, crumbly blue for this dish—particularly if you’re feeding a crowd that may include some picky eaters.

  • Resist the urge to swap out lower fat milk or cream. It’s a creamy, bubbly, buttery baking dish full of potatoes au gratin with Gruyére! It’s soul food, not health food. And that’s OK! Swapping out a lower fat dairy for the heavy cream and whole milk will result in a watery gratin, which is just no fun. Reserve this recipe for when you’re ready to live it up.

  • Leftovers can be stored in the fridge for 3-4 days, or frozen for up to 3 months.

potato leek au gratin made with Gruyère, parmesan, blue cheese, butter, cream, spices and ground mustard topped with chives

Super Satisfying Side Dishes From The Modern Proper

We Love Potatoes (And More!) At The Modern Proper

For more recipe inspiration, follow us on Facebook, Instagram, TikTok and Pinterest or order our cookbook. We love when you share your meals. Tag us on Instagram using #themodernproper. Happy cooking!

💌 Let's Stay Together

There are so many great ways to receive all of our latest recipes, meal tips, and inspiration.

Potato Leek Au Gratin

  • Serves: 8
  • Prep Time:  20 min
  • Cook Time:  1 hr 30 min
  • Calories: 389

Ingredients

  • 4 tablespoons salted butter, plus more for greasing
  • 3 pounds leeks, cut into ¼-thick slices
  • 1½ cups whole milk
  • 1 cup heavy cream
  • 2 ounces blue cheese, crumbled
  • 3 large garlic cloves, minced
  • 1 tablespoon stone ground mustard
  • ¼ teaspoon freshly grated nutmeg
  • ¾ teaspoon kosher salt
  • ½ teaspoon freshly ground black pepper
  • 6 ounces grated gruyère cheese
  • 2 ounces freshly grated parmesan cheese
  • 2 pounds russet potatoes, peeled and diced into ¾-inch pieces
  • 3 tablespoons minced fresh chives, plus more for serving

Method

  1. Preheat the oven to 400°F with a rack in the center position. Grease a 9x13-inch baking dish or a large cast iron skillet with butter.

  2. Melt the 4 tablespoons butter in a large nonstick skillet over medium heat. Once the butter is melted, add the leeks and stir to coat. Cover and cook, stirring occasionally, until the leeks are tender, about 15 minutes. Add the milk, cream, blue cheese, garlic, mustard, nutmeg, salt, and pepper. Simmer, uncovered, stirring occasionally, until slightly thickened, about 15 minutes more. Be careful not to boil. Remove from the heat, and let the mixture cool slightly in the skillet.

  3. In a large bowl, combine the gruyere and parmesan cheese.

  4. To the prepared baking dish, add ⅓ of the potatoes, then pour ⅓ of the leek mixture over top. Evenly sprinkle with ⅓ of the cheese mixture and 1 tablespoon of the chives. Repeat with the remaining ingredients.

  5. Cover the baking dish with foil and bake for 45 minutes. Remove the dish from the oven and discard foil. Return to the oven uncovered and bake until the potatoes are fork-tender and the crust is golden brown, about 30 minutes more. Let cool for 15 minutes.

  6. To serve, sprinkle with chives.

Nutrition Info

  • Per Serving
  • Amount
  • Calories389
  • Protein14 g
  • Carbohydrates47 g
  • Total Fat18 g
  • Dietary Fiber5 g
  • Cholesterol52 mg
  • sodium624 mg
  • Total Sugars10 g

Potato Leek Au Gratin

Questions & Reviews

Join the discussion below.

or
  • Annalea

    about how many leeks is this

    About 5, hope you enjoy Annalea!

  • Synthia

    Can I slice the potatoes like a traditional scallop or au gratin instead of cutting them in chunks?

    Sure!

  • rebecca

    looking to make this dish ahead of time and throw into the oven the day of - would you recommend making it in its entirety, refrigerating, and then throwing into the oven the day of or just making the leek mixture and assembling the rest of the ingredients the day of?

    Either way should work fine!

  • Sheila

    Could you substitute the blue cheese and gruyere cheese? If so, what would you recommend?

    in place of the gruyere you could try Beaufort, Comté, Jarlsberg, Emmental, or Fontina. You can try leaving it out or maybe adding goat cheese.

  • K

    Hi all ~

    I prepared my recipe with the yams 🍠! Not the sweet potato orange colored… the lighter colored yams!

    It was divine and doesn’t requires as much oven time (10-15 minutes less) to bake.

    Enjoy!

    Sounds delicious!

  • Mary

    I make this dish every major holiday it's so good I don't change a thing thank you

    Aw, that is so wonderful to hear. Thanks Mary, we are so glad you love it!

  • Mary

    Excellent recipe making it today didn't change a thing

    Thanks Mary, so glad you enjoyed it!

  • Hannah

    I made this dish for Christmas dinner and it was a BIG HIT. Thanks for the recipe! I've been requested to make a smaller portion to eat with the rest of the holiday leftovers, as the entire dish was demolished on Christmas. I subbed in a half pound of shallots because the bunch of leeks I bought weighed in at 2.5 lbs. I think it worked great.

    That sound delicious!