Everyone is sure to love this savoury-sweet Butternut Squash Gratin that screams Thanksgiving and Christmas. Oozing with creamy cheese and a crunchy bread crumb topping, I guarantee it will be the hit at your holiday table or any special occasion meal.
For our family, the appearance of this classic potato gratin on the Thanksgiving table is nonnegotiable. But because we already celebrated Thanksgiving here in Canada, I have a little freedom to play with tradition.
Not too dissimilar to a classic scallop potato dish, this gratin is instead made with thinly sliced butternut squash but it is just as cheesy and deliciously creamy. Bonus that it cooks a lot faster than a potato gratin and it is also a great dish for making ahead.
Brimming with comfort and coziness, this is the perfect side dish to a Sunday roast or the show-stopping centrepiece of your holiday table. I know you’re going to love it as much as we do.
About The Recipe
This butternut squash recipe is adapted from Ina Garten. Unquestionably, she is the queen of gratins and and this one is a huge favourite of ours, especially during the cold winter months. I essentially swapped out the potatoes from this recipe for butternut squash and used leeks instead of onions. We happen to looove fennel but I know fennel can be polarizing. I am willing to bet if I served you this gratin you would love everything about it and you wouldn’t even be able to detect there was fennel in it. It adds warmth to the gratin and it helps cut through some of the sweetness of the squash. If you really dislike it, just omit it. The gratin will still be delicious.
I also use less cream and cheese but the result is still an outrageously delicious dish and it really couldn’t be simpler to make. You start by sautéing sliced leeks, fennel, and minced garlic. Thinly sliced butternut squash rounds are layered with heavy cream, the sautéed vegetables, and nutty gruyère and parmesan. It then bakes for 30 minutes covered with parchment until the squash is tender.
I borrowed from another one of Ina’s gratin recipes, and scattered crunchy bread crumbs over top. The gratin then bakes until beautifully golden-brown and bubbly.
This is one of those dishes that looks like it requires a lot of skill and effort when in fact it is incredibly adaptable and practically foolproof. And while my family is not ready to give up their classic beloved potato gratin, this one is different enough that I see no reason to not serve both at our next holiday feast. Guess which one I’m having? 😉
Ingredients And Notes
- Butternut squash – You will need a large butternut squash for this recipe, weighing about 2 1/2 pounds.
- Fennel – Thinly sliced and sautéed in olive oil and butter, the earthy, mildly-sweet, anise-like notes of fennel pairs beautifully with the leeks and butternut squash. Keep in mind when fennel is cooked, its anise flavour is toned down considerably. But as I mentioned before, if you truly dislike fennel, you can leave it out.
- Leeks – Here leeks add a lovely depth of flavour to the gratin and are simply wonderful when smothered in cream and cheese. They are a little pricey at the moment so you can absolutely use an onion if you prefer.
- Garlic – Fresh garlic lends some intense savouriness to the dish.
- Olive oil – For sautéing the fennel, leeks, and garlic.
- Heavy cream – You really must use heavy cream here. Half-and-half or whole milk will not work. If avoiding dairy, you could use full-fat canned coconut milk.
- Gruyère – I pretty much always use Gruyère cheese in my gratins. It melts beautifully and has a rich and creamy, slightly nutty taste. You can also use Comté or any other good melting cheese such as Jarslberg, Fontina, or Emmental.
- Parmesan – Not essential, but I love the salty, almost umami flavour it lends to this dish.
- Fresh breadcrumbs or panko – I absolutely love the crunchy breadcrumb topping on this butternut squash gratin. Fresh breadcrumbs are always tastier, but panko works just as well. Gluten-free panko is easy to find if you are avoiding gluten.
- Salt and Pepper – Season with salt and pepper as you go. Like all starch-heavy dishes, this gratin needs plenty of seasoning.
- Butter – Optional for greasing the pan and dotting the breadcrumb topping.
- Pecans – Chopped pecans are a delicious crunchy topping on this gratin but I only add them for special occasions so feel free to omit them if avoiding nuts or if they are too expensive.
- Chives – Optional, but they add a nice pop of colour.
How To Make Butternut Squash Gratin
Slicing the butternut squash thinly is important so it doesn’t take too long to cook. A sharp knife will make the job quick and easy. Likewise, the fennel should be sliced really thin so it softens quickly when sautéed.
- Preheat the oven to 375ºF. Grease a 8-½ × 11-½-inch oval, or rectangular, shallow baking dish with butter.
- Heat the olive oil in a large skillet over medium heat. Sauté the fennel and leeks with a little salt, tossing occasionally, until soft and lightly browned, about 8 minutes. Add the garlic and cook for 1 more minute.
- Add the nutmeg, salt, and pepper to the cream and mix to combine.
- In the greased baking dish, layer 1/3 of the butternut squash slices in overlapping layers to cover the bottom of the dish. Season with ½ teaspoon of kosher salt and drizzle with 1/3 cup of cream. Scatter 1/3 of the leek mixture and 1/3 of the cheese mixture over top. Repeat this process of layering 2 more times but hold back on the last portion of cheese.
- Place a piece of parchment paper directly over the dish. Transfer to the oven and bake for 35-40 minutes. Carefully remove the baking dish from the oven and scatter the remaining cheese over the top followed by the bread crumb mixture and chopped pecans, if using. Return to the oven and bake until beautifully golden brown and bubbling, about 15 minutes more.
- Remove from oven and let cool for at least 15 minutes before cutting and serving.
How To Thinly Slice Butternut Squash
Butternut squash is quite easy to peel and slice. For this recipe, the butternut squash should be sliced into ⅛-inch-thick (or 1/4-inch) slices. I prefer to use a sharp knife as opposed to a mandolin to slice it because most mandolins aren’t big enough.
Once peeled, start slicing the neck of the squash into thin rounds until you get to the seeds. At this point, scoop out the seeds, cut the bulb in half and slice each half into ⅛-inch-thick slices.
Make Ahead Instructions
Some gratins are tricky to make ahead because the vegetables on the top layer can discolour or dry out, particularly when reheated.
However, unlike potatoes, or other white root vegetables, butternut squash gratin is notorious for staying moist and will not discolour so it keeps well for days when tightly covered and stored in the refrigerator.
Just bake the gratin without the bread crumbs then cool completely to room temperature. Cover tightly and refrigerate for up to 2 to 3 days. On the day you are ready to serve it, bake the gratin, covered with foil, at 375°F for 20 minutes. Remove foil, top with bread crumbs and bake for 10 to 15 minutes longer, or until gratin is golden and bubbly.
TIP: Remove the gratin dish from the refrigerator 30-60 minutes before baking. This will help it reheat faster and more evenly.
Don’t soak the sliced squash in water. Even a bit of extra moisture can make the gratin unpleasantly watery. In addition, placing the squash in water will wash away the starches which are essential to help thicken the cream.
Don’t use half and half or milk. You need heavy cream for this gratin. Anything with less fat content will curdle and will not thicken properly.
Adjust the amount of squash accordingly. The size and shape of your baking dish will affect the amount of squash you can fit. Buy an extra squash in case you need to fit more and add a tad more cream to the mix.
Season generously. I like to season the sautéed vegetables, the cream and the squash to ensure the dish is sufficiently seasoned.
Cover with parchment paper for part of the cooking. The butternut squash will cook quicker and more evenly if covered during some of the cooking time. I like to use parchment paper instead of foil so a great trick is to wet your piece of parchment under the faucet, crumple it up into a ball, then open it up shaking off any excess water. Now it will easily mold to the dish.
Freeze any extra butternut squash. My butternut squash was not very big but I had a bit leftover from the second one. If you have any leftover squash, cut it into chunks and freeze for up to 3 months. It will be great to add to soups or stews.
Leftovers of this butternut squash gratin are delicious the next day. In fact, as I am writing this post, I am enjoying a rather hefty portion of leftovers for lunch and it is absolutely scrumptious.
- To Store. Place cooked and cooled leftovers in an airtight storage container in the refrigerator for up to 4 days.
- To Reheat. Gently reheat leftovers in a baking dish covered with foil in the oven at 350 degrees F until warmed through. You may need to add a few splashes of cream if it seems really dry (mine usually isn’t). though I recommend the oven for the best texture.
More Thanksgiving Recipes To Try
- Honeynut Squash with Brown Butter
- Potato Au Gratin with Caramelized Onion
- Red Wine Cranberry Sauce
- Slow Cooker Turkey Breast
- Chicken Pot Pie
Butternut Squash Gratin
- 2 tablespoons butter, divided (or use all il if you prefer)
- 3 tablespoons Olive oil, divided
- 1 small fennel bulb, stalks removed, halved and cored, and sliced 1/4-inch thick
- 2 large leeks, white and light green parts, cleaned of all dirt thinly sliced
- Kosher salt and freshly ground black pepper
- 2 cloves garlic minced
- 2 1/2 pounds butternut squash peeled, and thinly sliced between 1/8 – inch thick *see photos in post for guidance
- 1/2 teaspoon nutmeg
- 1 cup heavy cream
- 1 cup grated gruyere cheese, divided about 3 ounces
- 1/2 cup grated parmesan
- 2 cups coarse fresh breadcrumbs or panko,
- 2 tablespoons chopped chives, optional for garnish
- Preheat the oven to 375ºF. Grease a 8-½ × 11-½-inch oval, or rectangular, shallow baking dish with 1 tablespoon butter (or oil).
- Heat 1 tablespoon butter and 1 tablespoon olive oil in a large skillet over medium heat. Sauté the fennel and leeks with a pinch of salt, tossing occasionally, until soft and lightly browned, about 8 minutes. Add the garlic and cook for 1 more minute.
- In a liquid measuring cup, mix the nutmeg, a 1/4 teaspoon salt, and 1/4 teaspoon pepper with the cream.
- Combine the gruyere and parmesan cheese in a small bowl.
- In the greased baking dish, layer 1/3 of the butternut squash slices in overlapping layers to cover the bottom of the dish. Season with 1/4 teaspoon of kosher salt and drizzle with 1/3 cup of cream. Scatter 1/3 of the leek mixture and 1/3 of the cheese mixture over top. Repeat this process of layering 2 more times but hold back on the last portion of cheese. Gently press down on the top of the gratin to ensure everything is laying as flat as possible.
- Place a piece of parchment paper directly over the dish. Transfer to the oven and bake for 30-40 minutes, or until vegetables feel tender when pierced with a fork.
- In a medium bowl, mix bread crumbs with remaining 2 tablespoons of butter until evenly coated. Set aside.
- Carefully remove the baking dish from the oven and discard the parchment. Scatter the remaining cheese over the top followed by the bread crumb mixture and chopped pecans. Dot with remaining tablespoon of butter, if using. Return to the oven and bake until beautifully golden brown and bubbling, about 15 minutes more.
- Remove from oven and let cool for at least 15 minutes before cutting and serving.