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Recipes » Side Dishes » A Butternut Squash Gratin With Parmesan And Rosemary

A Butternut Squash Gratin With Parmesan And Rosemary

As butternut squash roasts, naturally occurring sugars caramelize with heat resulting in a gorgeous golden ochre color, its flavor earthy and sweet.

featured image for Butternut Squash Gratin

A Butternut Squash Gratin With Parmesan And Rosemary

How Do I Make A Good Butternut Squash?

Roasting a butternut squash is super easy and it’s the best way to experience the fruit in its most basic state. As the squash roasts, the naturally occurring sugars will caramelize turning the squash a gorgeous ochre color. The flavor is earthy and sweet. The health benefits are a lengthy list. Rich in important vitamins, minerals, and disease-fighting antioxidants, this low-calorie and high fiber winter squash is not to be missed.

butternut squash

The recipe I am sharing with you is for you IF you like Parmesan cheese, garlic butter, and rosemary. AND, even if any of those three are making you question reading on, know that all three are substitutable. Basically, there is no good reason to skip this recipe…

There is so much more to fresh fall produce than just ‘pumpkin spice everything!’ If you are like me and want to cook moderately healthy but need practical shortcuts for weeknights and holiday dinners, I am here to remind you that all varieties of winter squashes are ripe and abundant now.

The recipe I am sharing with you is for you IF you like Parmesan cheese, garlic butter, and rosemary. AND, even if any of those three are making you question reading on, know that all three are substitutable. Basically, there is no good reason to skip this recipe…

Do You Have What’s Needed To Make A Butternut Squash Gratin With Parmesan And Rosemary? Check The List!

a butternut squash
olive oil
salted butter
sweet onion such as Vidalia
fresh garlic cloves
Parmesan cheese freshly grated from a block
fresh rosemary or fresh parsley leaves or a combination of both
lemon for zesting
panko bread crumbs
Malden salt or other flakey sea salt
ground black pepper

How This Recipe Came About…

Too many butternut, delicata, acorn, and pumpkin squashes coming out of my garden! I wanted to eat them all, well…all that I could not give away to friends and neighbors. But cooking up a squash every night would require a method for which I had ingredients already.

This method for a quasi gremolata of sorts with panko added for atop the squash became a recipe that I would add to and take away from over the years, keeping it simple versus making it difficult. The ingredients are few and the final dish a quasi-masterpiece representation of what it means to consume whole, unprocessed food.

squash on a vine

How To Peel A Butternut Squash?

  1. To soften the skin of a butternut squash for the purposes of peeling it EASILY, grab a large sharp kitchen knife. Remove both ends of the squash. About 3/4 to 1-inch will do.
  2. Now lay the squash on a piece of paper toweling on its side in your microwave. Zap the squash on regular power for 3 minutes.
  3. Once the microwave timer dings, you must use a towel or potholders to remove the hot squash from the microwave. I recommend allowing it to cool for at least 8 to 10 minutes (or longer in order to hold it safely if necessary).
  4. Use a vegetable peeler to start at one fleshy end, working the blade just under that skin to be able to run it all the way up. This method makes short work of the otherwise daunting task of peeling one of these bad boys.

Can I Use The Pre Cubed Squash I Find In My Grocers Fresh Vegetable Isle?

ABSOLUTELY! You’ll never hear me holding anybody back from a brilliant shortcut like pre cubed squash. I will however tell you to go fresh and LOCAL as often as you possibly can. Frozen cubed squash does not work in this recipe.

the inside of a butternut squash

How To Make Butternut Squash Gratin?

Once you’ve got your squash peeled, you must de-seed it. Slice the squash in half lengthwise. Using a large soup spoon, Gently scoop the pulp and the seeds out from the bulbus end of each half.

Turn the halves cut-side down on a cutting board and slice the squash into 1/2-inch thick slices, then into cubes. Pick one of your pretty casserole dishes and coat the bottom and sides with olive oil.

The remaining ingredients are cooked and combined to create a panko gremolata of sorts. I like to lift the cubes of squash here and there to ensure some of the panko gremolata makes it into the crevices as it roasts.

The gratin bakes for one hour or until it’s visibly tender and the panko gremolata topping is browned nicely.


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What If I Want The Butternut Squash Mashed?

Roasted butternut squash is easy, but I do recommend a couple of extra steps before your mashed squash can become a true dinnertime hit.

Peel, de-seed, and cube the squash. Toss the cubes into a large mixing bowl and add a good bit of olive oil, around two tablespoons. I toss the squash with Kosher salt and freshly ground black pepper before turning all out onto a foil-lined baking sheet.

Roast in 10 minute intervals at 425°F and flip and move around the baking sheet as needed to allow the squash to caramelize and turn golden brown on as many sides as is permitted without burning. All in all, about 30 to 40 minutes.

Remove from the hot oven and scrape right back into your mixing bowl. Use a hand held potato masher to mash and establish a chunky to smooth consistency.

This method for mashed squash is also the basis for many other dishes to include a delicious mac and cheese butternut squash soup as well as a sweet salad topper.

a white bowl with butternut squash

Modifying The Norm To Make It Not Entirely Average…

This dish is largely savory. If I were to modify any part of it to make it not entirely average, I might look to sweeten things up. The addition of maple syrup or a very light sprinkle of brown sugar and cayenne pepper combined would lend a different depth to this squash casserole.

Also, and in addition to the panko gremolata, a touch of light or heavy cream to be added to and baked off with the gratin would be lovely.

Can I Use Another Winter Squash Other Than Butternut Squash?

Absolutely. Delicata and pumpkin squashes are very similar in texture to butternut when cooked, so they are always viable choices. I like acorn squash and sweet potatoes (I know, NOT a squash!) for this, too.

What If I Need To Substitute Other Ingredients?

This recipe is relatively versatile which means there are absolutely some ingredient items that are easily replaced with other ingredient items. Be careful not to stray too far off course here. After all, this is a recipe for A Butternut Squash Gratin With Parmesan And Rosemary.

To substitute the onion, opt for shallots in the same measure. Their texture and flavor will compliment the squash very well.

To substitute the garlic-infused butter, muddle 1 tablespoon of the rosemary leaves with 1/4 dried sweet chili using a mortar and pestle. Really smash the contents to a chunky paste. Sauté along with the melted butter and chopped sweet onion.

To substitute the Parmesan cheese, purchase any number of hard cheeses. Among my favorites would be a well-aged Gouda or Beemster cheese.

a white bowl with butternut squash

Can Butternut Squash Gratin Be Made Ahead?

Yes…and no. In order to bust ahead with my task list at the holidays, I absolutely prepare the squash ahead of time and stop just before baking the casserole. Prepare the squash according to the recipe card as many as two days ahead.

The panko gremolata is something that takes mere minutes, and it’s crucial to have it be crispy fresh when it goes into a hot oven. Making the topping ahead would only result in a wimpy, wet panko.

My recommendation would be to prep every ingredient for the panko gremolata and incorporate them all at the last minute before topping off the squash and baking the lot.

Can Butternut Squash Gratin Be Frozen?

Yes, however I find the entire dish loses its moxie when its frozen, thawed, and reheated. Therefor, I do not recommend freezing before or after table service.

featured image for Butternut Squash Gratin

What To Serve With Butternut Squash Gratin?

This beautiful side dish compliments both sweet and savory dishes. I especially like it for a side dish at Thanksgiving and Christmas. I also find it easy enough a starch to prepare for a weeknight dinner alongside pork chops or chicken.

What To Drink With Butternut Squash Gratin?

Really, this clever side dish is amenable to most any red or white wine or beer that you plan to serve alongside main dishes. Therefor, focus on pairing your main rather than pairing this squash gratin.

If You Like This Recipe…

…you might also like:

Brown Butter French Green Beans With Toasted Pecans

Sweet And Tangy Carrots

Wild Rice & Butternut Casserole with Cranberries and Pecans

Buttery and Crispy Greek Lemon Potatoes

Maple Bacon Brussels Sprouts With Cipollini Onions

Jamie Oliver’s ‘Mothership’ Tomato Salad

Best Southern Corn Pudding

close up of creamy corn pudding

Best Southern Corn Pudding

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A Butternut Squash Gratin With Parmesan And Rosemary

Jenny from Not Entirely Average
As butternut squash roasts, naturally occurring sugars caramelize with heat resulting in a gorgeous golden ochre color, its flavor earthy and sweet.
No ratings yet
Servings: 4 servings
Prep Time 15 mins
Cook Time 1 hr
Total Time 1 hr 15 mins
Course Side Dish
Cuisine American
Servings 4 servings
Calories 294 kcal


  • vegetable peeler
  • Sharp Kitchen Knife
  • cutting board
  • large mixing bowl
  • baking dish


Ingredients For A Butternut Squash Gratin With Parmesan And Rosemary

  • 1 large butternut squash peeled, seeds removed, and cubed into 1/2-inch cubes
  • 2 tablespoons olive oil
  • 2 tablespoons salted butter
  • 1/2 cup sweet onion finely chopped
  • 6 cloves garlic smashed and chopped
  • 1/2 cup Parmesan freshly grated from a block, not from a can
  • 1 tablespoon lemon zest fresh
  • 3 tablespoons rosemary fresh, finely minced
  • 1 tablespoon parsley fresh, finely minced
  • 1/2 cup panko
  • 1 teaspoon, or more to taste Malden salt or other flakey sea salt
  • to taste black pepper freshly ground


The Method

  • Preheat oven to 350°F. Use a pastry brush to lightly coat the bottom and sides of a casserole dish. Set aside.
  • Peel the butternut squash (see my method for ease of peeling above). Slice in half lengthwise and scoop out seeds from the bulbus end of both halves. Cut into 1/2-inch thick slices, then into 1/2-inch cubes. Add to a large mixing bowl and set aside.
  • In a large non-stick skillet, sauté the finely chopped onion and the chopped garlic for 3 to 5 minutes over medium-high heat. You want the onion first translucent, but then to turn golden. Avoid allowing the garlic to burn by constantly moving the mixture around in the pan.
  • In a medium sized mixing bowl, combine the panko, grated parmesan, lemon zest, finely chopped rosemary, and finely chopped parsley and stir well to combine. Spoon enough of the garlic butter mixture into the panko mixture and stir until well combined, about 2 tablespoons.
  • Scrape the remaining garlic butter mixture into the cubed squash. Use a wooden spoon or rubber spatula to combine and coat all of the squash well. Turn out into the prepared baking dish. Arrange so the squash is evenly distributed from side to side. Season with the Malden salt and the black pepper.
  • Scrape the panko gremolata over the squash cubes. Use the tines of a fork to lift some of the cubes allowing the gremolata to fall between the crevasses of the squash.
  • Bake uncovered for 1 hour or until the squash cubes are sufficiently tender and the panko gremolata has turned a beautiful ochre color.
  • Serve immediately with additional fresh rosemary if desired.


Please Note that table salt and iodized salt are NOT substitutions for Kosher salt. Do not use table salt or iodized salt in any of the recipes you find on Not Entirely Average UNLESS specified otherwise. This recipe calls for Malden salt which is a flakey sea salt. If you are unable to locate Malden, use Kosher.
Substitute pre cubed fresh squash for whole fresh squash. Do not use frozen squash in this recipe.
Make ahead the actual squash up to two days in advance; peel, de-seed, and cube only, do not cook/bake the squash until the day it will be served. Panko gremolata must be made the day the gratin will be served.
Freezing Not Recommended this dish does not maintain its flavor or integrity once frozen. Refrain from freezing both before and after table service.


Serving: 1servingCalories: 294kcalCarbohydrates: 32gProtein: 8gFat: 17gSaturated Fat: 7gPolyunsaturated Fat: 1gMonounsaturated Fat: 8gTrans Fat: 1gCholesterol: 24mgSodium: 794mgPotassium: 752mgFiber: 5gSugar: 6gVitamin A: 20336IUVitamin C: 46mgCalcium: 289mgIron: 2mg
Keyword butternut squash, butternut squash casserole, butternut squash recipes mashed, christmas sides, how to make butternut squash, make butternut squash, mashed squash, Thanksgiving sides
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