This Butternut Squash and Sage Gratin is a delicious cheesy side dish (similar to scalloped potatoes). Thin sweet slices of butternut squash are baked in a fontina Parmesan cheese sauce, then topped with a crunchy panko breadcrumbs and baked. Ideal for Christmas and Thanksgiving dinner.

A cast iron skillet of butternut squash and sage gratin with serving spoons

What is gratin?

Any dish that is prepared in the French way ‘au gratin’, means that it is cooked in cream or milk with cheese and baked. This recipe is has a little twist by adding panko breadcrumbs for a lovely, crunchy topping.

Gratin serving dish

I recently purchased some small cast iron skillets because they’re just so cute. You can cook in them and serve the food right in the pan. I had a couple of butternut squash’s leftover over from making Thai butternut squash soup, so I came up with this gratin.

If you don’t have cast iron skillets, the recipe can also be made in an 8 x 8-inch (23 x 23 cm) square or oval baking dish.

Tried and true gratin recipe

If you’ve ever made a gratin or scalloped potatoes, you know that the milk or cream can curdle and/or the cheese separated and creates an oily layer. This is my foolproof recipe that avoid both of those.

The inside of butternut squash gratin showing the bright orange squash and creamy cheese sauce

When it comes to slicing the butternut squash, I recommend using a mandolin. The thinner the slices, the faster it bakes.

How to cut up a whole butternut squash

Start by cutting off the top end of the squash.

A whole butternut squash with the end cut off

Peel the entire squash.

Peeling a butternut squash

Cut the long neck part, as close to the bulbous end as possible. This is especially helpful for this recipe as you can cut as many rounds as possible.

Butternut squash cut into 3 parts

Cut the bulbous part in half and use a spoon to scrap out the seeds. 

Scraping the seeds out of a butternut squash

Then proceed to chop to the size needed.

Chopping a butternut squash

The best butternut squash for gratin

Choose a long neck butternuts squash, this way you can get lots of circles for the gratin. The best way to get thin slices is to use a mandolin, unless you’re skilled at slicing very thin with a sharp knife.

Best cheese for gratin

For the sauce, I took inspiration from the baked gnocchi with sage and cheese I made last year. The cheese sauce was so good it had to be repeated.

A cutting board with sliced butternut squash, fresh sage, parmesan cheese and grated fontina viewed from overhead

Which cheeses are best for gratin?

I always recommend the cook can use whatever good melting cheese they want when it comes to a cheese sauce. I can’t always find fontina in my store, so gruyere is a delicious alternative, sharp white cheddar or havarti are all lovely melting cheeses. It was recently recommended to me by a reader to try a mild gorgonzola. Parmesan is the best cheese to mix with the panko topping.

2 butternut squash and sage gratins in mini cast iron skillets

There is something just so flavorful with this sauce I wanted to eat the entire pan, but I was able to practise restraint, barely. Covered in a creamy, cheesy sage sauce and topped with sage panko breadcrumbs, how can that not make you drool?

2 mini cast iron skillets with butternut squash and sage gratin on a baking sheet ready for the oven

The Perfect Holiday Side Dish

This creamy butternut squash gratin is also the perfect holiday side dish. If you’re feeding a crowd, double the recipe and prepare in a larger 9 x 13-inch (23 x 33 cm) dish. It was such a hit for Thanksgiving, I made it again for Christmas because it was requested.

If you’ve tried this Butternut Squash and Sage Gratin or any other recipe on the blog then don’t forget to rate the recipe and let me know how it turned out in the comments. You can also ask questions there. I love to hear from my readers! 

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Yield: 4

Butternut Squash and Sage Gratin

A cast iron skillet of butternut squash and sage gratin with serving spoons

Sweet and creamy butternut squash, fontina & parmesan cheese sauce with fresh sage. 

Prep Time 15 minutes
Cook Time 40 minutes
Total Time 55 minutes


  • 1 pound (226 grams) butternut squash peeled and sliced, * see note
  • 4 tablespoons unsalted butter
  • 4 tablespoons all-purpose flour
  • 2 cups (272 ml) milk
  • 1 cup (50 grams) fontina cheese, grated
  • 2 cups (100 grams) parmesan cheese, freshly grated
  • 1 tablespoon fresh sage, chopped
  • ¼ teaspoon freshly grated nutmeg
  • ¼ teaspoon ground black pepper
  • ½ cup (40 grams) panko breadcrumbs


  1. Preheat oven to 375°F/190°C.
  2. Butter an 8 x 8-inch (20 x 20-cm) baking dish or mini cast iron skillets.
  3. Melt the 4 tablespoons butter in a pan over medium heat. Whisk in the flour until it absorbs the butter. Cook while stirring for 2 minutes to cook out the flour taste, it will start to turn darker when ready. Slowly whisk in the milk until thickened. Stir in the fontina and half of the Parmesan cheese until completely melted and sauce is smooth. Stir in the sage, nutmeg and pepper. Taste the sauce and taste for salt. This will depend on how salty your cheese is.
  4. Arrange ⅓ of the butternut squash slices in a single layer, slightly overlapping on the bottom of the dish.
  5. Pour ⅓ of the sauce over the first layer of butternut squash. Arrange another single layer of butternut squash and top with ⅓ of the sauce. Arrange the last layer of butternut squash and top with the remaining sauce.
  6. Mix the rest of the Parmesan cheese with the panko and mix well. Top the gratin with an even layer of the panko and a little more sage if desired.
  7. Place the dishes onto a baking sheet, cover with foil and bake for 30 minutes. Time will depend on how thickly you sliced the squash. Remove the foil and continue to bake until the top is golden and the butternut squash is tender when a fork is inserted. 
  8. Remove from the oven and allow to sit for 5 minutes before serving.


Choose a butternut squash with a long neck so you can cut in circles.

Nutrition Information



Serving Size


Amount Per Serving Calories 631Total Fat 40gSaturated Fat 23gTrans Fat 0gUnsaturated Fat 13gCholesterol 121mgSodium 1300mgCarbohydrates 41gFiber 5gSugar 10gProtein 30g

This nutrition calculation is provided by Nutronix that is only a guideline and not intended for any particular diet.