Cheesy Butternut Squash Casserole

Fall vegetables don’t get much better than butternut squash. I love how sweet and creamy it gets when you bake it just right. But let’s be honest – I’m not always in the mood to stuff and bake a whole squash when I want something comforting for dinner.

That’s where this butternut squash casserole comes in handy. You get all that good squash flavor without the hassle of dealing with a giant gourd on your counter. I can cube everything up, toss it together, and pop it in the oven while I help the kids with homework.

Want something that feels fancy but doesn’t require fancy skills? This is it. Need a side dish that’ll make your family think you spent hours in the kitchen? Same recipe. I make this for regular weeknight dinners and holiday tables alike.

What Kind of Butternut Squash Should I Use?

Any butternut squash you find at the grocery store will work great for this casserole, but there are a few things to keep in mind when selecting one. Look for a squash that feels heavy for its size and has a hard, matte skin without any soft spots or blemishes. The neck of the squash (the long, straight part) should be nice and thick since that’s where you’ll get the most usable flesh. If you’re short on time, many stores now sell pre-cut butternut squash cubes in the produce section, which can be a real time-saver even though they cost a bit more.

Options for Substitutions

This fall-inspired casserole is pretty forgiving when it comes to swaps:

• Butternut squash: You can easily swap this with acorn squash, delicata squash, or even sweet potatoes. Just keep the cooking time about the same since they have similar textures.
• Honeycrisp apples: Any firm apple works here – try Granny Smith for more tartness or Gala for extra sweetness. Just avoid soft apples like Red Delicious that might turn mushy.
• Sweet Italian sausage: Ground turkey or chicken sausage makes a lighter option, or try spicy Italian sausage if you want more heat. You could even skip the meat entirely for a vegetarian version.
• Fennel bulbs: If fennel isn’t your thing or you can’t find it, substitute with thinly sliced celery or even more onion. You’ll lose that subtle licorice flavor, but the dish will still be tasty.
• Gruyere cheese: Swiss cheese is the closest substitute, but sharp cheddar or even Parmesan work well too. Just use about the same amount.
• Herbes de Provence: Make your own blend with dried thyme, rosemary, and oregano, or just use Italian seasoning in the same amount.

Watch Out for These Mistakes While Cooking

The biggest mistake when making butternut squash casserole is cutting your squash and apples into uneven pieces, which leads to some chunks being mushy while others stay hard – aim for uniform medium-sized cubes so everything cooks at the same rate.

Don’t skip browning the Italian sausage properly before adding it to the casserole, as this step builds flavor and prevents the meat from releasing too much grease during baking.

Another common error is adding the Gruyere cheese too early in the baking process, which can cause it to become tough and rubbery – sprinkle it on during the last 15-20 minutes of cooking for the perfect melted finish.

Make sure to slice your fennel thin enough so it softens completely, and if your squash seems to be browning too quickly on top, cover it with foil and continue baking until fork-tender throughout.

What to Serve With Butternut Squash Casserole?

This hearty casserole is perfect as a side dish for your holiday table alongside roasted turkey, ham, or pork tenderloin. The sweet and savory flavors also pair beautifully with simple roasted chicken or even grilled lamb chops for a cozy dinner. Since it’s already packed with sausage, apples, and cheese, you could easily serve it as a main dish with just a crisp green salad dressed with lemon vinaigrette to balance out the richness. For a complete fall feast, try it with roasted Brussels sprouts, cranberry sauce, and some warm dinner rolls for soaking up all those good flavors.

Storage Instructions

Store: This butternut squash casserole keeps really well in the fridge for up to 4 days when covered tightly with foil or plastic wrap. The flavors actually get even better after a day or two, so it’s perfect for making ahead for Sunday dinner or meal prep for the week.

Freeze: You can freeze this casserole for up to 3 months in a freezer-safe dish or container. I like to wrap it really well in plastic wrap and then foil to prevent freezer burn. Just remember to thaw it completely in the fridge overnight before reheating.

Reheat: To warm it back up, cover with foil and bake at 350°F for about 20-25 minutes until heated through. If you’re reheating from frozen, it’ll take closer to 45 minutes. You might want to sprinkle a little extra cheese on top and remove the foil for the last few minutes to get that nice golden finish again.

Preparation Time	20-30 minutes
Cooking Time	45-60 minutes
Total Time	65-90 minutes
Level of Difficulty	Medium

Estimated Nutrition

Estimated nutrition for the whole recipe (without optional ingredients):

• Calories: 1550-1750
• Protein: 50-60 g
• Fat: 70-80 g
• Carbohydrates: 170-190 g

Ingredients

For the roasted squash and apples:

• 2 honeycrisp apples (peeled, cored, and diced similar to the squash)
• Salt, to taste
• 2 lb butternut squash (peeled and cut into 1-inch cubes)
• 1/2 tsp dried sage
• 1 1/2 tsp herbes de provence
• 1 tbsp maple syrup
• Black pepper, to taste
• 2 tbsp olive oil (I use California Olive Ranch extra virgin)

For the sausage and vegetables:

• 1 onion (cut into thin strips)
• 2 small fennel bulbs (thinly sliced)
• 1/2 lb sweet italian sausage (casings removed and crumbled)
• Olive oil, as needed

For assembly and topping:

• 1 tbsp maple syrup
• 1/4 cup oil (for frying sage, optional)
• Fresh sage leaves (for garnish)
• Salt and pepper, as desired
• 1 cup shredded Gruyere cheese (provides a nutty flavor)

Step 1: Roast the Butternut Squash and Apples

• 2 lb butternut squash, peeled and cut into medium cubes
• 2 Honeycrisp apples, peeled, cored, and diced to match squash size
• 2 tbsp olive oil (divided as needed)
• generous salt, to taste
• black pepper, to taste
• 1 tbsp pure maple syrup
• 1/2 tsp dried ground sage
• 1 1/2 tsp herbes de provence

Preheat your oven to 425°F and line a baking sheet with foil, lightly misting it with cooking spray.

In a large bowl, combine the cubed butternut squash and diced Honeycrisp apples.

Drizzle about 2 tablespoons of olive oil over the mixture, then sprinkle generously with salt and black pepper.

Add 1 tablespoon pure maple syrup, dried ground sage, and herbes de Provence.

Toss everything together to evenly coat.

Spread the mixture out on the prepared baking sheet and roast for about 35 minutes, stirring occasionally for even roasting, until the squash is tender.

Step 2: Cook the Sausage

• 1/2 lb sweet Italian sausage, casings off and broken up
• additional olive oil, as needed

While the squash and apples are roasting, heat a large skillet (cast-iron works great) over medium-high heat.

Add a small drizzle of olive oil.

Once the pan is hot, add the crumbled sweet Italian sausage.

Cook for a few minutes, stirring occasionally, until the sausage is browned and cooked through.

Remove the sausage from the skillet and set aside in a bowl.

Step 3: Caramelize the Fennel and Onion

• 2 small fennel bulbs, halved, cored and thinly sliced
• 1 onion, cut into quarters and thin strips
• additional olive oil, as needed

If the skillet looks a bit dry, add a touch more olive oil.

Add the sliced fennel and onion to the pan and cook over medium heat, caramelizing together for about 10-12 minutes.

Stir occasionally until the vegetables are deeply golden and jammy in texture.

Remove from the pan and add to the bowl with the cooked sausage.

I like to give the pan an extra minute on low to really bring out the sweetness in the vegetables.

Step 4: Combine and Assemble the Casserole

• roasted butternut squash/apples from Step 1
• sausage/fennel/onion mixture from Steps 2 and 3
• 1 tbsp maple syrup
• extra salt and pepper, as desired

Switch your oven setting to broil.

In a large bowl, combine the roasted butternut squash/apples (from Step 1) with the sausage, fennel, and onion mixture (from Steps 2 and 3).

Pour in the remaining 1 tablespoon maple syrup and toss everything together to blend flavors.

Season with salt and pepper to taste, creating a sweet-savory balance.

Transfer the mixture to a medium baking dish, about 9 by 13 inches.

Step 5: Fry Sage Leaves (Optional)

• fresh sage leaves (for garnish — use fresh or fried)
• 1/4 cup oil (for frying sage, optional)
• extra salt and pepper, as desired

If you’d like a crispy sage garnish, heat 1/4 cup oil in a small saucepan over medium-high heat.

Once shimmering, add the sage leaves and fry for about 20 seconds until crisp.

Immediately remove the leaves to a paper towel to drain, and sprinkle lightly with salt.

Set aside for garnishing later.

Step 6: Broil the Casserole with Gruyere

• 1 cup gruyere cheese, shredded

Top the assembled casserole (from Step 4) with the shredded Gruyere cheese.

Place the baking dish under the broiler for a few minutes, just until the cheese is melted and golden-brown.

Keep a close eye, as broilers can brown things quickly!

I like to use real Gruyere, but a mix of Gruyere and Swiss works well too.

Step 7: Garnish and Serve

Remove the casserole from the oven and let cool slightly.

Garnish with either fried sage leaves (from Step 5) or fresh sage leaves.

Serve warm and enjoy the blend of sweet, savory, and herbal flavors.