Potato Leek Gratin with Crispy Breadcrumbs

Name: Potato Leek Gratin with Crispy Breadcrumbs
Prep time: 20 min
Cook time: 1 h 30 min
Total time: 1 h 50 min
Ingredients: 3 tablespoons butter, divided; 2 medium leeks, white and light green parts only, halved lengthwise and sliced into half-moons; 1 1/4 pound Yukon gold potatoes, peeled if desired, sliced into 1/8-inch-thick rounds; 1 large clove garlic, minced; 1/4 teaspoon dried thyme; Pinch of ground nutmeg; 1 cup heavy cream; 6 ounces Gruyère cheese, shredded; 3 ounces Parmesan cheese, shredded; 1 teaspoon kosher salt; 1/2 teaspoon freshly ground black pepper; 1/2 cup Panko breadcrumbs; Finely chopped chives, for topping

Dec 14, 2022 · 432 Comments

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This creamy, cheesy Potato Leek Gratin is topped with crispy, buttery breadcrumbs before being baked to tender perfection. The best holiday side dish!

Potato leek gratin with a scoop taken out, showing the layers of thinly sliced potatoes inside.

Ya know those recipes that are so good you’re tempted to lick the plate? Yeah, this potato leek gratin is one of them. (And it may cause you to literally lick the plate.) I’m already all-in for cheesy, creamy potatoes in any form, but when you top them with crispy, golden-brown breadcrumbs, it’s game over.

This gratin is THE perfect side dish for the holidays, but don’t feel like you have to wait for a special occasion to make it. Whenever you’re craving cheesy, creamy comfort, it’s here for you. It loves you. It never disappoints.

And the best part is that, while it feels special, it’s not too difficult to make. If you can slice a potato, you can make this gratin! Beyond slicing potatoes, the hardest part is exercising patience while it bakes. But when it comes out of the oven, you’ll be rewarded for your efforts a thousand fold. Seriously — you’re gonna love this one.

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Ingredients
Instructions
Substitutions and Variations
Expert Tips
Equipment Needed
Make-Ahead Tips
Storage Tips
FAQs
Potato Leek Gratin with Crispy Breadcrumbs

Ingredients

Less isn’t always more, but in the case of this gratin, it is. Just a handful of simple, high-quality ingredients come together to create a memorable dish. To make it, you’ll need:

Butter. Salted or unsalted will work just fine for this. You’ll need three tablespoons total — one for the cream sauce, one for the breadcrumbs, and one to butter the baking dish.
Leeks. If you haven’t cooked with leeks before, this is your sign! They’re a delicious member of the allium family (read: related to onions and garlic), and they look a bit like an oversized green onion. Wash them well after you slice them because they’re notorious for being dirty.
Yukon gold potatoes. I strongly prefer gold potatoes for this recipe because of their rich, buttery flavor and waxy texture. I don’t recommend russets for this recipe due to their high starch content.
Garlic, dried thyme and nutmeg. Just a little of each, because potatoes, cheese and leeks should be the star of the show!
Heavy cream. Cream really works best here — I don’t recommend swapping it out for half-and-half or milk in this recipe because they can result in a watery gratin.
Gruyère and Parmesan cheese. Gruyère is a Swiss-type cheese with a slight salty nuttiness I love. You can typically find it with the other higher-end cheeses at the grocery store.
Panko breadcrumbs. These, of course, put the “crispy breadcrumbs” in “potato leek gratin with crispy breadcrumbs.” You can usually find them by the Asian foods in the international aisle of the grocery store. They’re bigger and crispier than Italian-style breadcrumbs.

A saucepan full of creamy leek sauce, ready to be layered in a potato gratin.

Instructions

While it feels fancy, this gratin is actually really simple to make. Slicing the potatoes takes some time and energy, but you can enlist the help of a mandoline if you’d like (as long as you promise to use the safety guard!). Here’s what you’ll do:

Do all your prep work: Slice up your leeks and clean them really well. Leeks can get pretty dirty, so make sure you’re getting rid of all that sand between the layers. Slice the potatoes into thin rounds. (If they’re not perfect, that’s okay!) Shred the cheese and mince the garlic.
Butter a casserole dish or 8×8-inch baking pan and preheat the oven to 350°F.
Make the creamy leek sauce: Melt butter on the stove over medium heat. Add the sliced leeks and cook ’em for a few minutes until they start to soften, then add the garlic, thyme and nutmeg. Pour in the cream and season with salt and pepper. Simmer for a couple minutes to thicken it a bit, then set it aside.
Layer everything in the dish: We’ll create three layers of potatoes, cream sauce and cheese, kinda like a potato-y lasagna. Shingle your potato slices in the bottom of the baking dish in a single layer. Pour over about a third of the cream sauce and scooch it around with your spoon so all the potatoes are covered. Sprinkle on a third of the cheese, then repeat this process until you’ve filled the dish.
Make the breadcrumbs: Melt some butter in the microwave and stir in the breadcrumbs, along with a pinch of seasoning. Sprinkle the breadcrumbs evenly over the top of the gratin.
Bake: Cover the baking dish with foil and bake for 30 minutes.
Uncover and bake again: Remove the foil and return to the oven to bake once more for about 45 minutes, or until the potatoes are tender.
Top with chives and serve!

An assembled, unbaked potato leek gratin topped with lots of Gruyère and Parmesan cheese.

Substitutions and Variations

If you can’t find leeks, you can use one small yellow onion instead. Slice it as thinly as you can and proceed with the recipe as directed.

Gruyère is delicious, but it can be expensive or hard to find. For a close substitution, use Swiss cheese instead. Really, though, this recipe would certainly be delicious with just about any cheese (because it’s cheese).

Expert Tips

While it can be tedious to slice potatoes super thin, I promise it will be worth the time and effort. Make sure you’re slicing them as thin as you can — it’s better for the texture and it takes less time to bake.

An overhead shot of a potato leek gratin topped with crispy breadcrumbs and chopped chives.

Equipment Needed

Make-Ahead Tips

You can make this gratin the night before and bake it the day of. Just assemble through step 4, then cover with foil and refrigerate overnight. Two hours before serving, pop it into the preheated oven and bake as directed in steps 5–7.

Storage Tips

This gratin keeps incredibly well in the fridge and is (in my humble opinion) even better left over! Store it in an airtight container for 3–4 days. To reheat, warm it in a 350°F oven for about 20 minutes, or until piping hot.

Potato leek gratin scooped out onto a plate with a fork.

FAQs

Can I use half-and-half or milk to lighten things up?

I’m usually all for healthier swaps, but this is one recipe where I truly don’t advise it. Heavy cream is necessary to create that thick, creamy sauce. Swapping it out for a lighter alternative will result in a watery gratin. Save this recipe for when you’re ready to indulge!

Can I use different types of cheese in this gratin?

I love the subtle nuttiness of Gruyère, but it can be expensive! You can swap it out for any Swiss cheese to get a similar flavor. Just make sure you’re buying blocks of cheese and shredding them yourself — pre-shredded cheese has anti-caking agents that can mess with the texture and prevent it from melting as nicely.

Do I have to use the breadcrumb topping?

Definitely not! This gratin is perfectly delicious without the crispy breadcrumbs on top, so feel free to skip them if you’d rather. As a bonus, omitting the breadcrumbs makes this recipe gluten free, if that’s something you’re after.

More comforting holiday recipes:
Slow Cooker Mulled Wine
Cranberry Meringue Pie
Hot Honey Brussels Sprouts

Did you make this recipe? If you loved it, please leave a ⭐5-star rating⭐ and/or leave a comment below the recipe card! And don’t forget to share a photo and tag me on Instagram, Facebook or TikTok — I love seeing you recreate my recipes.