This Butternut Squash and Sage Gratin is a delicious cheese casserole side dish, but could also be a meal in itself. Sweet and creamy butternut squash is baked in a fontina & Parmesan cheese sauce, topped with a crunchy panko breadcrumb topping. Ideal for Christmas and Thanksgiving dinner.

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

Any dish that is prepared in the French way ‘au gratin’, means that it is topped with cheese and breadcrumbs and baked.

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 roasted butternut squash bruschetta and I wanted to make a rich creamy dish, a gratin came to mind. If you don’t have cast iron skillets, the recipe can also be made in an 8 x 8 inch square or oval baking dish.

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

Gratin makes a really good sauce: 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, but this time I used milk instead of chicken stock because the butternut squash can hold up to the heavy sauce.

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

Which cheeses are best? 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 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 dish. It was such a hit for Thanksgiving, I made it again for Christmas because it was requested.

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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 whole butternut squash peeled and sliced, 1 1/2 to 2 pounds
  • 4 tablespoons unsalted butter
  • 4 tablespoons all-purpose flour
  • 2 cups milk
  • 1 cup fontina cheese, grated
  • 2 cups parmesan cheese, freshly grated
  • 1 tablespoon fresh sage, chopped
  • 1/4 teaspoon freshly grated nutmeg
  • 1/4 teaspoon ground black pepper
  • 1 cup 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 sauté 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.
  4. Whisk in the milk, in small batches until thickened. Stir in the fontina and 1 cup of Parmesan cheese until completely melted and sauce is smooth.
  5. Stir in the sage, nutmeg and pepper. Taste the sauce and add more salt. This will depend on how salty your cheese is and your salt palette.
  6. Arrange the butternut squash slices in a single layer on bottom of dish.
  7. Pour 1/3 of the sauce over the first layer of butternut squash. Arrange another single layer of butternut squash and top with 1/3 of the sauce. Arrange the last layer of butternut squash and top with the remaining sauce.
  8. Mix the other cup of Parmesan cheese with the panko and mix well. Top the gratin with an even layer.
  9. Place the dishes onto a baking sheet and bake for 40 minutes until the top is golden and the butternut squash is tender when a fork is inserted. 
  10. Remove from the oven and allow to sit for 5 minutes before serving.

Nutrition Information



Serving Size


Amount Per Serving Calories 646Total Fat 39gSaturated Fat 23gTrans Fat 1gUnsaturated Fat 13gCholesterol 118mgSodium 1401mgCarbohydrates 44gFiber 3gSugar 9gProtein 31g

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