Butternut Squash Gratin with Leeks, Sage and Walnuts – a delicious vegetarian side dish, highlighting the best of fall ingredients, worthy of the holiday table! Vegan-adaptable. With a Video!

 Butternut Squash Gratin with Leeks, Sage and Walnuts - a delicious vegetarian side dish, highlighting the best of fall ingredients, worthy of  the holiday table! Vegan-adaptable!

We can’t decide what we like best about this Butternut Squash Gratin- the melted leeks, the toasted walnuts, the fresh sage, or the hint of nutmeg that infuses the whole thing with goodness.

Think of this like scalloped potatoes, but made with butternut squash instead.  Hearty and satisfying, this is pure and total comfort food.

I suppose one might categorize this as a Thanksgiving side dish and yes- that is what it was designed for, but truth be told, we’ve been eating this for “dinner” the last few nights, along with a salad and sourdough bread and couldn’t be happier. Use it as you please.

The recipe makes a big batch- enough to serve eight, so feel free to cut this in half for smaller gatherings.

Butternut Squash Gratin Video

 Butternut Squash Gratin with Leeks, Sage and Walnuts - a delicious meatless side dish, highlighting the best of fall ingredients, worthy of  the holiday table! Vegan-adaptable! #butternutsquash #gratin #sidedish #thanksgivingrecipes

Ingredients in Butternut squash Gratin:

butternut gratin ingredients- leeks, butternut, cream, gruyere, sage, walnuts

How to make Butternut Squash Gratin:

Start by preheating the oven to 375F and peeling the butternut squash.

peel the butternut squash

Slice as thinly as possible- aiming for 1/8 of an inch. The thinner the slices the faster this will cook.

slice the butternut squash

When you get to the seeds, scoop them out and keep slicing.

scoop out the seeds

We will hide the half-moons in the middle layer of the gratin.

cut into ⅛ inch slices

Slice the leeks, rinse well, and saute until meltingly tender.

saute the leeks

Add the fresh sage leaves.

chop the sage leaves sauté the sage

Mix up the heavy cream with the seasonings.

Here we are using heavy whipping cream, feel free to use half and half or plant-based cream or coconut milk if you like.

season the cream

Then begin layering all the ingredients.

Grease a 9×13 inch baking dish, or a shallow round 11-12-inch baker like you see here. TIP: A large shallow baking dish is key here to getting this to bake evenly and quickly.

Add 1/4 cup water to the greased baking dish. Then start layering the butternut and 1/2 of the leek mixture. Top with cheese and 1/3 of the cream sauce.

layer the gratin

For the middle layer, add all the scraps and half moons, saving the prettiest slices for the top layer.

Sprinkle  with leeks and cheese and a little of the cream mixture.

layer the butternut gratin

layering the gratin with more leeks

Here below is the top of the second layer. I’ve hidden all the misshapen pieces of butternut in this middle layer.

Top with the final layer of butternut slices- layering a little if need be.

The final layer of the gratin

Spoon the remaining cream mixture over top.

Sprinkle with cheese and the toasted walnuts.

top with cheese, walnuts and fresh grated nutmeg

And if you like, add an additional sprinkling of freshly grated nutmeg.

fresh grated nutmeg

Cover tightly and bake for 45 minutes.

Then uncover, turning the heat up to 4oo for 10-15 more minutes until beautifully golden

Garnish with crispy sage leaves if you like.

Can this be made ahead?

Yes, this can be assembled ahead and baked the day of serving, bringing it to room temp before baking. Alternatively, this can be baked ahead and reheated in a low 325-350F oven, covered (also bringing to room temp before reheating).

Can this be frozen?

Probably. My hesitation is it might get watery- but only guessing here. If you freeze this, please report back and let us know in the comments.

Can this be made vegan?

Yes, I think so! Use vegan parmesan and a vegan cream or plant-based cream. Lite Coconut milk from a can would taste good, I bet. Please let us know if you try this- leaving notes for others- thanks!!!

 Butternut Squash Gratin with Leeks, Sage and Walnuts - a delicious vegetarian side dish, highlighting the best of fall ingredients, worthy of  the holiday table! Vegan-adaptable! #butternutsquash #gratin #sidedish #thanksgivingrecipes

Give this Butternut Squash Gratin a try this Thanksgiving and let us know what you think (or ways you adapt it) in the comments below.



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 Butternut Squash Gratin with Leeks, Sage and Walnuts - a delicious meatless side dish, highlighting the best of fall ingredients, worthy of  the holiday table! Vegan-adaptable! #butternutsquash #gratin #sidedish #thanksgivingrecipes

Butternut Gratin with Leeks, Sage and Walnuts

5 Stars 4 Stars 3 Stars 2 Stars 1 Star 5 from 39 reviews
  • Author: Sylvia Fountaine| Feasting at Home
  • Prep Time: 40 mins
  • Cook Time: 60 mins
  • Total Time: 1 hour 40 minutes
  • Yield: 8 1x
  • Category: side dish, vegetarian
  • Method: baked
  • Cuisine: American
  • Diet: Vegetarian


Butternut Squash Gratin with Leeks, Sage and Walnuts – a delicious vegetarian side dish, highlighting the best of fall ingredients, worthy of the holiday table! Vegan-adaptable!


Units Scale
  • 2 lb butternut squash, peeled, sliced to 1/8 inch disks.
  • 2 tablespoons olive oil or butter
  • 2 medium leeks, thinly sliced
  • 4 garlic cloves, rough chopped
  • 15 sage leaves, chopped (8 more for crispy sage leaf garnish- optional)
  • ——
  • 1 cup heavy cream (or sub coconut milk)
  • 1/2 teaspoon salt and pepper
  • 1/2 teaspoon nutmeg
  • 1/2 teaspoon onion powder, optional
  • ——-
  • 1/4 cup water
  • 3 ounces gruyere cheese (or sub parmesan or vegan parmesan)
  • 1/2 cup walnuts, chopped


Preheat oven to 375 F

  1. Prep Butternut: Peel and thinly slice the butternut squash into 1/8 -inch thick rounds. When you get to the seeds, scoop them out and continue slicing. Set aside 12-15 of the “prettiest” slices for the top of the gratin. ( There will be 3 layers of butternut – so you could divide into 3, placing any misshapen pieces in the middle layer)
  2. Cook the Leeks: Slice and rinse the leeks- the moisture here will help them soften. Heat oil or butter in a large skillet over medium heat. Saute the leeks, for 8-10 minutes, covering part way through so they soften. Add the garlic, sage and a pinch of salt, cook 2-3 more minutes. Turn heat off.
  3. Whisk the cream with the salt, pepper, nutmeg and onion powder in a medium bowl.
  4. Layer: Grease a large 9 x 13-inch baking dish or 11-12 inch round baking dish. A big shallow pan is BEST here ensuring even cooking.  Grease the pan, add 1/4 cup water to the bottom of the pan. Layer with Butternut squash overlapping slightly. Sprinkle with half of the sauteed leeks. Drizzle with 1/3 cup cream mixture. Sprinkle with one ounce of Gruyere (about 3-4 tablespoons grated). Add the 2nd layer of butternut- using up any misshapen pieces here. Scatter with the remaining leeks. Drizzle with 1/3 cup cream mixture and sprinkle with grated gruyere cheese. Add the final layer of butternut, overlapping and pressing down so not domed in the middle. Drizzle the remaining cream mixture over top, lightly sprinkle with cheese and the walnuts. Give the pan a little shake, press down in the center again so gratin is level, not domed. Cover, using parchment first as a barrier, under the foil if the foil touches the top of the gratin.
  5. Bake 45 minutes covered. Uncover, confirming the butternut is tender using the tip of a knife, then bake at 400 F uncovered, 15 minutes until beautifully golden.
  6. To make the crispy sage leaf garnish, heat 1-2 tablespoons oil or butter in a pan over medium heat, add 8 whole sage leaves, saute each side 30 seconds or so until crisp (try a tester first) and place on a paper towel to cool for a couple of minutes. Arrange over the gratin.


This can be made ahead: Assemble ahea, refrigerate, and bake the day of serving, or alternatively, assemble and bake ahead, reheating the day of serving (350F, covered). Make sure to let this come to room temp before baking or reheating for most even cooking.

I have not tried this with cubed butternut, but if I were to go that route, I would toss them in a big bowl, with the cream mixture and leeks and cheese. Bake in a large shallow baking dish and allow 20-30 more minutes additional baking time depending on the size of the cubes.  Thinly sliced butternut makes this bake relatively quickly- cubes would take longer, so plan accordingly. (Or you could lightly steam or cook them first?)


  • Serving Size: - used heavy whipping cream and olive oil
  • Calories: 201
  • Sugar: 4.3 g
  • Sodium: 239.5 mg
  • Fat: 12.7 g
  • Saturated Fat: 6.1 g
  • Carbohydrates: 19.3 g
  • Fiber: 3.1 g
  • Protein: 5.4 g
  • Cholesterol: 28.7 mg

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  1. Omigod this is the most incredible recipe! It’s so light yet complex in flavour, I actually could eat the whole thing in one. I made this as one of my holiday recipes, a couple of days after making a potato gratin and I much preferred this recipe as it was far less heavy and yet ten times more flavourful. Thank you for your wonderful recipes!

  2. Another hit! I made this with coconut milk and subbed parmesan for the Gruyère. I also used a little mozzerella because I had it on hand. It was so good and tasted so much like scalloped potatoes! I loved the sage and walnut in it. It was a great side for our simple thanksgiving dinner and was easy to throw together the day of!

  3. We enjoyed your dish on Thanksgiving. I made a vegan version with lite coconut milk and we enjoyed your recipe. Next time I will just add a little more of the nutritional yeast flakes to give it a more cheesy kind of flavor. Leek is a staple in German kitchens, I was excited to see leek as an ingredient in your recipe smile. I will explore your other recipes and look forward cooking this recipe again. Thank you from Ingrid and Family

  4. Hi, I made your recipe yesterday and we enjoyed it. I used a lite coconut milk, with the seasonings and made vegan Parmesan. Next time I will add additional nutritional yeast flakes to get some more cheesy flavor. I am from Germany and leek is a staple in the kitchen. I was glad to find your recipe!

  5. Hello, I’m looking to substitute sweet potatoes for the butternut squash. Do you think it will require the same baking time? Thank you

    1. Great question, I’m not sure here. My guess is it would be close. But test with a knife when you remove foil to be sure.

  6. Hi, can this be frozen at any stage? Am guessing not before its cooked, but maybe after? And maybe add the walnuts and crispy sage when you re-heat? What do you advise, please?

    1. Hi Jane- I would freeze it after it is baked- and like you said add the nuts and sage after. That’s what I would do too. 😉

  7. Haven’t yet made it—it looks and sounds great! I just wanted to mention to you that the recipe portion specifies to cut the squash in 18 inch thick pieces—when 1/8 inch thick pieces is meant.

  8. Hi Sylvia, if we wanted to add crumbled sausage to this, would we just mix it in raw with everything else? Or would you recommend cooking it first?

    Just want to make sure it would be fully cooked when the veggies are. 🙂

    Thank you! We’re huge fans of all your recipes.

  9. Delicious! I used pecans instead of walnuts. I plan to use this as a holiday side in the future.

  10. Hi Sylvia, I made this last night, simply delicious. I replaced the walnuts with pecans.I decided to freeze the leftovers, I hope everything will turn out well. Thank you for another great recipe.

    1. Thanks and great to hear Carole- let us know how it turns out after you thaw it…curious!

  11. I’ve made this several times now and always really enjoy it. Thank you!
    Other than parmesan, do you have any suggestions to substitute the gruyère? It is unfortunately very expensive where I live. And I like to use a lot 🙂

    I tried freezing it as leftovers in portions and it turned out a little bit mushy but still flavourful. I didn’t mind eating it as leftovers after freezing but I don’t think I’d choose to freeze it if I wanted to serve it to guests or something.

    For those who, like me, don’t care as much about the aesthetics and get tired of chopping, I have had good results quartering the solid parts of the squash and running them through my kitchen aid’s slicer attachment to speed up the process. They come out less pretty and a bit thinner but it saves me lots of time.

    1. You know- I bet most meltable cheese would be ok here. Mozzarella, even maybe some goat cheese?

  12. Hi – I am going to make this for Christmas as a side. If I make ahead and reheat at 350- how long do you think it needs to reheat for? Just trying to time everything! Thanks!

    1. If you let it come to room temp first, probably 25-30 minutes? Perhaps cover with foil for first half?

  13. I used your recipe for my first time cooking with butternut squash, and it turned out great. One thing I wondered – should I actually whip the heavy cream with the other ingredients, or simply combine and leave liquid? Some of it started whipping when I mixed it up.

    My partner commented that she would like this gratin inside ravioli, so I’m trying to figure that out next 🙂

  14. I made the vegan version and loved it! I added nutritional yeast to the coconut cream as suggested (thanks for that!) and was very happy with the outcome. I also used the remaining coconut water from the can instead of water. Thanks for another delicious and healthy recipe, Sylvia!!

  15. There are no instructions for toasting the walnuts. Won’t they toast as part of the baking? Has anyone tried this with pecans instead? Anyway, made this 2x now and it is DELICIOUS. Now my go to for fall and winter gatherings. Thank you so much!!!

  16. This recipe turned out delicious!!! However the milk (I used half and half) curdled while baking. It still tasted fantastic, however the curdled milk was a little weird. Any suggestions on how to avoid this? The half/half came right out of fridge. Was it too cold? Should milk be brought to room temp before using? It came out of the fridge cold and I baked as soon as I assembled it. Any thoughts on how to avoid this? I’m making it for Thanksgiving, I know it taste delish, just need to solve that issue. Thank you!!!

    1. Hi Elisabeth, it was the half and half. Sorry about that. The heavy creamy won’t curdle. Neither will the coconut milk. I removed the half and half as an option. Again, my apologies.

      1. Ah! Okay. Hmmm I don’t have heavy cream and store not open tomorrow, I do have plenty of coconut milk though. The canned kind. That will work? And does it give it a different taste? I have to say, the recipe was delicious…just a
        bumpy : )

        1. Canned coconut milk will work great. Or you could try making a light bechamel sauce out of your half and half. I haven’t tried heating it, so that might work too.

          1. Thank you so much for your quick response. I’ll give the coconut milk a try! I love your website and it is my “go to” for recipes. Happy Thanksgiving!

      2. I used coconut milk this time and it turned out fabulously!!!! It was a huge hit on Thanksgiving, delicious, and will be making this dish for a long time to come. Everyone asked for the recipe! Thank you so much!

  17. This looks delicious! I am making it for Thanksgiving. I just wanted to confirm the correct amount of butternut squash; is the weight given in the recipe after peeling and prepping it, or is that the weight of the whole squash? I just put my whole squash on the scale and it weighs 4.1 pounds. Thank you!

    1. Hi Beth! Good question. And I’m trying to remember! I think it would be safe to say, 2 lbs peeled and deseeded!

      1. Thank you! The walnuts are toasting as I type and I am about to break down the squash. Thank you so much for sharing this recipe! Have a wonderful Thanksgiving.

  18. Absolutely wonderful easy impressive tasty side dish that could be used for many occasions. Used homegrown squash and herbs from my garden. Great re heated up for leftovers for the next few days, Made a day ahead and served with Lamb Shanks. Thanks Sylvia.

  19. This is one of the best recipes with butternut squash! I have made so many variations and all are delicious. The last one was with blue cheese and cashew cream with smoked paprika and it was amazing. Thanks so much Sylvia!


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