Butternut Squash Gratin

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 for Thanksgiving dinner is nonnegotiable. But because we already celebrated Thanksgiving here in Canada, I have a little freedom to play with other holiday meals.

Not too dissimilar to a classic scallop potato dish, this gratin is instead made with thinly sliced butternut squash. But trust me, it is just as luscious, 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.

Why You Will Love This Recipe

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. It is adapted from Ina Garten, which is almost reason enough to know you’re going to love it.

I essentially swapped out the potatoes from this recipe for butternut squash, and used leeks instead of onions. Ina uses fennel with her potato gratin and here it works beautifully paired with the squash. I Know fennel can be polarizing but I urge you to give it a try. It really adds lovely warmth to the gratin and it helps cut through some of the sweetness of the squash. If you really dislike fennel, just omit it. The gratin will still be delicious.

Finally, the butternut squash gratin is baked with an outrageously delicious buttery, crunchy panko and pecan topping that makes it even more irresistible. Best of all, this dish comes together really fast, does not take too terribly long to bake, and leftovers are scrumptious for days.

Ingredient Notes And Substitutions

• 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 a large yellow 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 as they could split and make the gratin taste greasy. 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 breadcrumbs 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 also be sliced really thin so it softens quickly when sautéed.

Here is an overview of the recipe. Full measurements and instructions can be found in the printable recipe card below.

• Preheat the oven to 375ºF. Grease a 8-½ × 11-½-inch oval, or rectangular, shallow baking dish with butter.
• Heat the olive oil and butter 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.
• In a large mixing bowl, combine the heavy cream, nutmeg, salt and pepper. Add all the butternut squash slices, 3/4 cups of gruyere cheese and leek mixture. Toss to combine, then transfer to prepared dish. Gently press down on the top of the gratin to ensure everything is laying as flat as possible. 
• In a medium bowl, combine remaining gruyere cheese with breadcrumbs and pecans (if using). Evenly spread over top of squash. Dot with remaining tablespoon butter, cut into pieces.
• Cover tightly with aluminum foil and bake for 30-40 minutes, or until squash feels tender when pierced with a fork. 
• Remove the foil and bake until beautifully golden brown and bubbling, about 10 to 15 minutes more. 
• Let cool for at least 15 minutes then garnish with chives, if using, before slicing 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 or 1/4-inch-thick rounds. 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 half moon 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 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.

Storing Tips

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 350ºF until warmed through. You may need to add a few splashes of cream if it seems really dry (mine usually isn’t).

What To Serve With Butternut Squash Gratin

This squash gratin is the perfect Thanksgiving or holiday meal side dish. It pairs beautifully with this spatchcocked turkey or with a rib roast. We also love it with a roasted chicken, or a simple pork roast.

It would also make a great vegetarian main alongside a salad or other vegetables such as roasted broccoli or cauliflower.

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

More Ideas