This post may contain affiliate links. Please read our disclosure policy.
The ultimate savory Butternut Squash Casserole with Parmesan-creamed kale, nutty Gruyere cheese, and a toasted walnut-sourdough topping. This stunning side dish will be the hit of your next holiday gathering.
Today, we’re stepping outside the box of classic holiday casseroles with this epic butternut squash recipe.
The casserole filling boasts creamy butternut squash, plus the addition of hearty kale to up its nutritional value and balance the sweetness of the squash.
And since no proper casserole worthy of its name should be without a topping, this beauty is finished with a crispy Parmesan and walnut sourdough crust to make it truly memorable.
While the casserole is filled with many good-for-you nutrients, the addition of classic holiday flavors from thyme and walnuts ensure it feels right at home at a holiday gathering.
How to Make Butternut Squash Casserole
You will feel like the holiday MVP serving this casserole to a crowd. It’s the perfect alchemy of sweet, herby, savory, and crunchy to bolster any side dish spread.
It may even convert the most staunch veggie skeptics into believers!
The Ingredients
- Butternut Squash: A golden jewel of winter produce, butternut squash is wonderfully sweet, nutty, and pairs beautifully with fall flavors. You need 1 (2.5 lb.) squash for this recipe, which will yield about 2 lbs. of peeled and cubed squash
- For convenience, you can also purchase the containers of peeled and pre-sliced squash.
- Kale: Packed with fiber and immune-supportive vitamins, kale helps create an impressive nutrition profile for this casserole. Sautéing it first creates a tender, toothsome texture that will impress even the biggest kale skeptics.
- Onion: You need one medium yellow onion, which you can swap for shallots or sweet onion.
- Garlic: I love to REALLY amp up the garlicky goodness of this casserole with 5 cloves. You can certainly adjust this amount to your taste preferences.
- Heavy Cream: To create a luxuriously creamy filling, 1 cup of heavy cream does all the heavy lifting. Alternatively, you can use cashew cream or full-fat coconut milk.
- Cheese: A mix of savory, salty Parmesan and creamy, nutty Gruyere cheese create the ultimate power pair.
- Sourdough: Torn sourdough bread creates a delightfully crispy crust on the casserole. Alternatively, you can use panko breadcrumbs here for convenience.
- Walnuts: Beloved for their richness, crunch, and heart-health benefits, chopped walnuts help elevate the topping.
Pro Tip: To turn this side dish into entree material, you can add meat! Stir in browned, crumbled Italian sausage (or chicken sausage) for a hearty fall dinner. 
The Directions:
Step 1: Sauté the Aromatics
Preheat oven to 425ºF.
Heat olive oil in a large sauté pan over medium heat. Once hot, add onion; cook for 7 to 8 minutes, until soft. Stir in garlic and red pepper flakes; cook 2 more minutes.
Step 2: Add Kale and Cream
Stir in kale and cook until softened, about 3 to 4 minutes. Stir in heavy cream, 1/3 cup Parmesan cheese, fresh thyme, Dijon mustard, salt and pepper; simmer mixture until slightly thickened, about 5 minutes.
Step 3: Assemble and Bake Casserole
Arrange squash in a greased baking dish. Carefully pour kale mixture over butternut squash, stirring to make sure it gets into all the crevices. Scatter Gruyere cheese overtop.
Loosely cover casserole with foil and bake at 425ºF for 30 minutes.
Step 4: Prepare Topping
In a medium bowl, combine sourdough, walnuts, remaining 2 Tbsp. Parmesan, and olive oil. Massage oil into bread mixture until well-coated.
Remove casserole from oven and discard foil. Scatter sourdough mixture overtop and return casserole to the oven. Bake for 15 minutes, until the squash is tender and filling is thickened. Broil for the final 1 to 2 minutes for a more browned crust, if desired. 
How to Cut Butternut Squash
While it may seem intimidating, butternut squash is much easier to peel and chop than it appears!
- Start by selecting your squash. I find ones with longer necks are easier to peel and handle.
- Use a SHARP chef’s knife to cut off both the top and bottom of the butternut squash, about 1/2 of an inch from the end (this helps stabilize the squash while you peel and cut).
- Using a durable vegetable peeler (either swivel peeler or a Y-Peeler) or a sharp chef’s knife, peel off the outer skin of the butternut squash.
- With the same chef’s knife, cut the squash crosswise where the neck of the squash meets the rounder base end. Stand each of the pieces upright on your cutting board and make a cut down the middle from top to bottom. You’ll now have 4 pieces.
- Use a spoon to remove the seeds and stringy parts from the inside the base of the squash.
- Lay your halves cut side down, and cut each half into 1-inch wide slabs. Next, cut your slices crosswise in 1-inch wide cubes. Note: not all of the pieces will be a perfect cube (the base end ones are especially oblong), however you can further trim them depending on your desired shape/size.
Tools to Make this Recipe:
- Baking Dish: For an elegant transition from oven to table, I use my 10.75 x 7.5-inch Staub Ceramic Baking Dish. Staub baking dishes are oven and broiler safe up to 572F, as well as microwave and dishwasher safe. They also boast a beautiful vitreous glass porcelain-enamel finish. I especially love the rustic red color for the holidays.
- Sauté Pan: I use my Staub 12-inch Cast Iron Sauté Pan, which is large enough to hold the filling ingredients without worrying about spillover. The cast iron possesses exceptional heat-retaining qualities, so the pan heats evenly throughout.
- Chef’s Knife: A sharp chef’s knife will especially come in handy for cutting the butternut squash. I personally love my Zwilling Pro Le Blanc Chef’s Knife, which is a reliable, sturdy knife for all veggie chopping endeavors.
Make-Ahead and Storage Tips:
- To Make-Ahead: Peel and cube the butternut squash up to 3 days ahead. You can also stem and chop the kale up to 1 day ahead. Refrigerate each in a separate airtight storage container.
- Store: Cover and refrigerate leftover casserole for up to 5 days.
- To Reheat: For best results, rewarm leftovers in a baking dish in the oven at 350ºF. You can reheat in the microwave in a pinch.
- To Freeze: Freeze casserole in an airtight freezer-safe storage container for up to 3 months. Let thaw overnight in the refrigerator before reheating in a 350ºF oven.
More Thanksgiving Casserole Recipes to Try:
The Best Broccoli Cheese Casserole
Vegan Green Bean Casserole
Wild Rice and Cheesy Broccoli Casserole
If you give this recipe a try, be sure to snap a pic and tag #dishingouthealth on Instagram so I can see your creations. Also, follow along on Facebook and Pinterest for the latest recipe updates!
Cheesy Butternut Squash Casserole
Equipment
- 11x7 or 13x9-inch baking dish
Ingredients
- 4 Tbsp. extra-virgin oive oil, divided
- 1 medium yellow onion, finely chopped
- 5 garlic cloves, minced
- 1/4 to 1/2 tsp. crushed red pepper flakes (depending on desired level of heat)
- 1 bunch lacinato kale, stems and ribs removed, chopped
- 1 cup heavy cream
- 1/3 cup, plus 2 Tbsp. grated Parmesan cheese, divided
- 1 Tbsp. Dijon mustard
- 1 Tbsp. fresh thyme leaves
- 3/4 tsp. kosher salt
- 1/2 tsp. black pepper
- 2 lbs. peeled and cubed butternut squash
- 1/2 cup shredded Gruyere or gouda cheese
- 2 cups torn or roughly chopped sourdough bread
- 1/3 cup finely chopped walnuts
Instructions
- Preheat oven to 425ºF.Heat 2 Tbsp. olive oil in a large sauté pan over medium heat. Once hot, add onion; cook for 7 to 8 minutes, until soft. Stir in garlic and red pepper flakes; cook 2 more minutes.
- Stir in kale and cook until softened, about 2 to 3 minutes. Stir in heavy cream, 1/3 cup Parmesan cheese, Dijon mustard, fresh thyme, salt and pepper; simmer mixture until thickened, about 3 to 5 minutes.
- Arrange butternut squash in a greased 3-quart baking dish. Carefully pour kale mixture over butternut squash, stirring to make sure it gets into all the crevices. Scatter Gruyere cheese overtop.Cover casserole with foil and bake at 425ºF for 30 minutes, until the squash becomes nearly fork-tender. (Note: if your squash is still hard at this point, bake for an additional 10 minutes.)
- Meanwhile, combine sourdough, walnuts, remaining 2 Tbsp. Parmesan, 2 Tbsp. olive oil, and a small pinch of salt in a medium bowl. Massage oil into bread mixture until well-coated.Remove casserole from oven and discard foil. Scatter sourdough mixture overtop and return casserole to the oven. Bake, uncovered, for 20 more minutes, until the squash is tender and filling is thickened.Let stand 5 to 10 minutes before serving.
Notes
- To Make-Ahead: Peel and cube the butternut squash up to 3 days ahead. You can also stem and chop the kale up to 1 day ahead. Refrigerate each in a separate airtight storage container.
- Store: Cover and refrigerate leftover casserole for up to 5 days.
- To Reheat: For best results, rewarm leftovers in a baking dish in the oven at 350ºF. You can reheat in the microwave in a pinch.
- To Freeze: Freeze casserole in an airtight freezer-safe storage container for up to 3 months. Let thaw overnight in the refrigerator before reheating in a 350ºF oven.
Nutrition
I calculate these values by hand to ensure accuracy, however expect up to a 10% variable depending on food brands.
This was INSANELY delicious!!! Thank you for this gorgeous recipe
I missed the part about covering with foil, so my end product wasn’t as creamy as the picture, but it was delicious still. We ate some leftovers last night and it only improved with age! Will definitely add this to my recipe file!
This is my go to casserole to bring to holiday dinners. I get requested for it year after year! It’s so so good.