Leek, Carrot and Potato Gratin – A Perfect Side Dish

This leek, carrot and potato gratin is one of my favourite ways to enjoy the last of the garden veggies.

leek carrot and potato gratin in dish
Three layers of leeks, potatoes and carrots in between cheese and a white sauce.

Also Read: Leek & Potato Soup, Dehydrating Leeks, Types of Potatoes, Harvesting and Storing Carrots

Loaded with cheese and a white sauce, this dish is a hearty, filling side dish. It works equally well for simple weeknight dinners or for a fancy Thanksgiving dinner. With three layers of leeks, potatoes and carrots sandwiched between cheese and sauce, this recipe will feed up to eight people.

spoon full of gratin
Delicious, hearty comfort food!

Common Questions About Gratins

Are Gratin Potatoes the Same as Scalloped Potatoes?

No. There’s one big difference – cheese. Gratins, whether potato au gratin or leek, carrot and potato au gratin include cheese. The cheese may be layered separately, as in my recipe, or it can be melted into the sauce. But there is definitely cheese. Scalloped potatoes, also very delicious, are made using only the white sauce.

What Type of Potatoes to Use?

I like using white or yellow potatoes that are in the middle of being waxy (red potatoes) or starchy (russet)(read choosing potatoes). White or yellow potatoes will hold their shape nicely but will also soak up the sauce thanks to their starchy texture. That said, any type or combination of potatoes will work, the layers of the gratin may just not be as distinguishable if you use starchier potatoes. In this recipe, the carrots help keep the layers in tact – so go ahead use whatever potato you have access to.

layering the gratin
Here’s a look after the first layer is done. Notice I’m using a mix of red and yellow potatoes because that’s what we harvested!

What if I don’t have Leeks?

No problem, use an onion instead. Leeks have a slightly different, milder flavour, but onions will work in this recipe. I would use one sliced medium onion.

How Long will Leftovers Last?

Any extras will last in the fridge for three to four days. They reheat well in the microwave, oven or in a frying pan (our favourite method). FYI – they taste great with fried eggs for breakfast!

Can You Freeze This Dish?

Yes, after being cooked and cooled, you can freeze au gratins. Usually, freezing potatoes is not recommended, but because they are smothered in a rich, high fat sauce, you can wrap tightly and freeze this dish for up to 6 months.

baked gratin
Bake until bubbly and golden then garnish with greens. If the top is getting too brown – cover with lid or foil until potatoes and carrots are fork tender.

Can You Make this Dish Ahead?

Yes, you can make it up to a day or two ahead and keep well covered in the fridge. Just be sure all the potatoes, especially those on top, are well covered with sauce to prevent any discolouring. I would not recommend freezing this dish uncooked.

Recipe for Leek, Carrot & Potato Gratin

baked gratin
Print Recipe
5 from 8 votes

Leek, Carrot and Potato au Gratin

A delicious, creamy side dish featuring leeks, carrots and potatoes layered between cheese and a creamy sauce. A perfect side for any feast. Assemble a day ahead and cook the day of the feast.
Prep : 15 mins
Cook : 50 mins
Total Time: 1 hr 5 mins
Servings: 8 people
Author: Getty Stewart


  • 3 Tbsp butter, divided
  • 3 medium leeks, thinly sliced
  • 2 cloves garlic, minced
  • 2 Tbsp all purpose flour
  • 11/2 cups whole milk
  • 1/2 tsp salt
  • 1/4 tsp black pepper
  • 1/4 tsp dry mustard powder
  • 2 sprigs fresh thyme (1/2 tsp dried)
  • 3 large red or white potatoes (1 lb), thinly sliced (1/8 inch)
  • 2 large carrots, thinly sliced (1/8 inch)
  • 11/2 cups shredded melting cheese (cheddar, gruyere, Swiss, Fontina, mozzarella)
  • 1 Tbsp fresh chopped chives or parsley to garnish


  • Preheat oven to 375°F/ 190°C and generously grease or butter a 21/2 quart/litre baking dish.
  • In medium pan, sauté leeks in 1 Tbsp butter until tender, about 5-7 minutes.
  • Add garlic and sauté another 1-2 minutes.
  • Remove leeks from pan and set aside.
  • In same pan, melt remaining 2 Tbsp butter.
  • Mix in flour until all of the butter is absorbed.
  • Gradually whisk in milk to make a smooth sauce.
  • Add salt, pepper, mustard powder and thyme. Stir and heat until sauce is thick and smooth. Taste and adjust seasoning to your liking. Remove from heat.

Assembly & Baking

  • Layer the gratin in prepared dish in thirds. Start with 1/3 potatoes, leeks, carrots, top with 1/3 cheese, top with 1/3 sauce. Repeat two more times finishing with sauce.
  • Bake, covered for 30 minutes. Uncover and bake another 25 to 30 minutes until vegetables are tender. To test tenderness, insert a knife through layers.
  • Remove from oven and let rest for 10 minutes to set. Garnish with fresh chives or parsley.


Want to change the cheese – go for it! Use your favourites.
Want to skip the carrots – no problem. Make this gratin the way you want!
Want to add a layer of bread crumbs and parmesan on top – that would be mighty tasty and a classic au gratin touch.
Tried this recipe?Mention @GetGettyS or tag #GetGettyS

Nutrition Facts (per serving)

Calories: 562kcal | Carbohydrates: 29g | Protein: 28g | Fat: 38g | Sodium: 795mg | Fiber: 3g | Sugar: 12g | Iron: 2mg
Course: Side Dish
Cuisine: French
Keyword: leeks, potato au gratin, Thanksgiving side dish

What To Serve with Leek, Carrot & Potato Gratin?

This is a hearty side dish that we typically eat with some sort of meat that isn’t in its own sauce. Think roast chicken, turkey, beef, pork or ham. Also BBQ meat or fried eggs go well with this dish.

We also like steamed or seasoned, roasted veggies on the side. Again, because this gratin is already saucy and cheesy the veggies don’t need their own sauce.

A nice, light green salad on the side would also lighten things up.

A sample dinner menu might look like this:

Roast Chicken

Leek, Carrot & Potato au Gratin

Fresh Citrus Salad

Best Berry Cobbler

spoon full of gratin
I love leftovers of this gratin. Perfect when heated in a fry pan next to a fried egg.

Ready to try making this gratin? Will you make any substitutions? Let me know how it goes, down below in the comments or on Instagram @GetGettyS or on Facebook @GettyStewart.HomeEconomist.

Sign up to get articles by Getty delivered to your inbox. You’ll get recipes, practical tips and great food information like this. Getty is a Professional Home Economist,  speaker and writer putting good food on tables and agendas.  She is the author of Manitoba’s best-selling Prairie Fruit Cookbook, Founder of Fruit Share, a mom and veggie gardener.

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