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!
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 Gratin Video
Ingredients in Butternut Gratin:
- 2 lb butternut squash
- 2 leeks
- Gruyere cheese (or vegan parmesan cheese)
- heavy cream ( or plant-based cream, milk or coconut milk)
How to make Butternut Squash Gratin:
Start by preheating the oven to 375F and peeling the butternut squash.
Slice as thinly as possible- aiming for 1/8 of an inch. The thinner the slices the faster this will cook.
When you get to the seeds, scoop them out and keep slicing.
The half-moons, we will hide in the middle of the gratin.
Slice the leeks, rinse well and saute until meltingly tender.
Add the fresh sage leaves.
Mix up the cream with the seasonings.
Here we are using heavy whipping cream, feel free to use half and half or plant-based cream if you like.
Then begin layering all the ingredients. Use a 9×13 inch baking dish, or a shallow round 11-12-inch baker like you see here.
A large shallow baking dish is key here to getting this to bake evenly and quickly.
There are 3 layers of butternut, so save the prettiest slices for the top.
Sprinkle the two bottom layers with leeks and cheese and a little of the cream mixture.
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.
Spoon the remaining cream mixture over top.
Sprinkle with cheese and the toasted walnuts.
And if you like, add an additional sprinkling of freshly 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!!!
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.
More recipes you may like:
- 25 Vegan & Vegetarian Side Dishes
- Parsnip Gratin with Gruyere and Thyme
- Cauliflower Gratin with Garlic and Sage
- Tomato Zucchini Gratin
- Butternut Lasagna with Mushrooms and Sage
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!
- 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
- Prep Butternut: Peel and thinly slice the butternut squash into 18 -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)
- 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.
- Whisk the cream with the salt, pepper, nutmeg and onion powder in a medium bowl.
- 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.
- 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.
- 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?)
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