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. This was easy and delicious! I didn’t have a few items (leeks, sage, Gruyère, and walnuts!) so I substituted a white onion, dried herbs, Parmesan, and pecans…my husband LOVED it and we will definitely make it again. Could do for everyday OR company! Thanks for a new favorite recipe!

  2. Hi Sylvia,
    Do you it would be possible to mix butternut squash and potatoes in this recipe? I want to do potato au gratin and this wonderful butternut squash recipe so I wonder if it would be a good combo or it may not turn out the best? Thanks for the insight!

    1. It sounds good to me! I guess my only hesitation is if they would cook in the same amount of time? Seems like it should be fine?

  3. I’m going to try making this for my future daughter in law for Thanksgiving. She is a vegetarian and I want at least a couple of special dishes for her. This sounds amazing! I’m going to try it out at home first!

  4. Wonderful combination of the butternut, leeks,sage, walnuts, cheese. I did an “skinny” weeknight version by just baking it with the leeks butternut, a bit of broth instead of water, skipped the cream. Baked till done then on each serving could add as much or as little cheese as wanted. This was a great side dish. I would do it the way you have done for a special dinner though. A favorite.

  5. Made it vegan! It was excellant.
    I used blue ribbon plantbase cooking cream.
    Violife grated mozzarella (could not find parmasan)
    I had friends over for dinner and they loved this. I will making it again.

  6. This recipe is simply exquisite — except for one problem: the water added to the bottom of the pan was unnecessary and nearly ruined my gratin by making the bottom very watery and sludgy. (I’d even used a bit less water than called for.) I was able to save it by serving half with a slotted spatula and then leaving the pan resting at an angle to drain the remaining half before transferring it to a storage container. Other than this issue, it came together beautifully! The flavors are to die for, and I’m looking forward to making it for company sometime. Thanks!

      1. I can’t explain that part, either, but your recipe is one of my top 3 favorite butternut dishes. (Your roasted butternut soup is another!) 3# of sliced squash, 3 leeks, and 1.5c cream fit my 9×13″ pan perfectly.

      2. I think I see where there is confusion about the water. In the preamble discussion on how to make the recipe you state put some of the cream mixture in bottom of dish. In the recipe section there is no mention of this but it states to put water in the buttered dish and then start layering. I’m making this for company tonight so hopefully not adding the water works😬🤞🏼🙏

        1. Cindy- please follow the recipe card for the best outcome. Hopefully it worked for you!

          1. Yes I did add the water as the video I finally was able to view also showed adding the water. The recipe was delicious and turned out wonderfully.

      3. Hi there, I find my “just picked” butternut to be more watery then an aged/cured one. Also this year up here in VT rain was plentiful. The dryer squash perhaps need the extra moisture? (Also the leeks need their moisture cooked out, the video does a nice job on that!)

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