Flavor packed butternut squash casserole with caramelized mushrooms, shallots and apples. It's topped with an oat crumble with a little fig jam for a perfect savory and sweet combination! This post was originally published on November 2013 and updated December 2021.
This great butternut squash recipe also shares shortcuts, make ahead tips, ways for roasting butternut squash, and includes an option of including quinoa for a vegetarian main dish.Jump to Recipe
I roast up a lot of butternut squash during the fall and early winter months. And this butternut squash casserole is one of my favorite ways to use it. This article answers the question of how healthy is butternut squash, ways to roast butternut squash and tips for making this casserole.
How Healthy is Butternut Squash?
It's true that butternut squash is high in carbs, it's also loaded with antioxidants, vitamins (such as Vitamins A and C), and fiber. It's low in calories and has a low glycemic index. This means it's digested more slowly, which keeps blood sugar levels from rising quickly.
I think of butternut squash and sweet potatoes as interchangeable in many recipes. Both are healthy choices, but don't have the same nutrient package. Both pack a nutritional punch, but sweet potatoes are higher in calories and carbs (sugars).
Roasting Butternut Squash
There are a few ways to approach roasting butternut squash. Deciding which to use largely depends on how you'll use it.
Roasting Butternut Squash Whole
Preheat the oven to 375˚F (190˚C).
Using a sharp chef's knife, slice off the top to remove the stem, and cut the butternut squash in half lengthwise. If the skin is too tough to cut through, place the squash in the microwave for 5 minutes, and try again. The steaming in the microwave should loosen the skin enough to cut through.
Scoop out the seeds and pulp with a spoon. A grapefruit (serrated) spoon works even better, but a regular spoon in your drawer will be fine. Place the squash in a baking dish, cut side up. Brush all surfaces of the squash, except the outer skin with olive oil, and lightly season with salt and pepper.
Roast for 30 - 45 minutes, depending on the size of the squash. If you're in a hurry, you can also add a little water to the baking dish, cover it with plastic, and microwave on high for 10 minutes. Then remove the plastic and slide into the oven to roast for 15 minutes, or until tender.
Roasting Butternut Squash Cubed
Peel the squash using a vegetable peeler. I like the Y-shaped vegetable peelers for this. Then, using a sharp chef's knife, slice off the stem, and cut the squash in half lengthwise.
Scoop out the seeds and pulp with a spoon.
Flip over each butternut squash half, cut sides face down, and slice into ¾" cubes. Place the cubes in a large bowl, drizzle a little olive oil over them and toss with your fingers to completely coat the cubes.
Roasting butternut squash cubes in the oven
Line a baking sheet with parchment paper, and spread the cubes across the sheet, making sure there's space between each cube. Lightly season with salt and pepper. Roast in a 400˚F (204˚C) for 30 - 35 minutes for ¾" cubes. Smaller cubes will roast faster.
Roasting butternut squash cubes in the air fryer
Place the cubes in the air fryer basket and roast in the air fryer at 375˚F (190˚C) for 15 minutes for ¾" cubes.
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Butternut Squash - you only need 4 cups, cubed, so a smaller butternut is perfect. If you have more left over, cut it all into cubes, roast, and save what you don't need for this recipe. Add them to salads, fold into tacos or burritos, or just serve tossed with a little sage as a side.
Or use them, with caramelized shallots or onions to make Butternut Squash Empanadas!
If you prefer, you can use sweet potatoes in place of the butternut, or even cubes of delicata squash (although I haven't tried it).
Mushrooms - you don't need anything fancy here. Button mushrooms work great.
Shallots - if you don't have shallots on hand, use yellow onion instead.
Thyme - feel free to swap this out for other herbs you like with butternut squash and apples.
Balsamic Vinegar - this deepens the umami flavor of this butternut squash casserole, so don't skip this!
Apples - any apple that works great in baking is suggested, except Granny Smith apples. They're too tart for this casserole.
Dried Cherries - you can swap these out for golden raisins, cranberries or dried figs.
Fig Jam - The fig jam adds a wonderful contrasting sweetness with the savory butternut squash - mushroom filling and buttery crumble. Any fig jam will work, since you don't need much of it.
Other Ingredient Ideas
I've made this casserole many times, with numerous variations. Here are some of my favorites.
Stir 1 cup cooked quinoa into the roasted butternut squash to turn it into a main vegetarian / vegan dish. Dot the top with a few little pats of butter. Check this article out for more ideas on increasing the protein content in this butternut squash casserole.
Adding torn shards of kale are another nice addition. Sauté them in the pan with the mushrooms and onion, but only after they've caramelized.
Toss in some cheese before sliding the casserole into the oven. I personally like freshly grated Gruyere.
I've made this with the crumble topping, topped with lattice pie crust, and without any topping at all. We prefer the crumble, followed by no topping at all.
Caramelizing the mushrooms and onions together takes a little time, but it's time well spent. This is the umami flavor base for this butternut squash casserole. As they cook, be sure not to move them around much, else they won't caramelize. The pan should be completely dry, and a nice fond developed on the pan when you're done.
It's important to cover the casserole with foil for the first part of the baking process, as this will help keep the casserole moist.
Combine the crumble ingredients with your fingers or a pastry blender only until the butter pieces are about the size of a pea. Much smaller than that, and it's more of a pie crust than a crumble topping.
Purchase butternut squash already cubed. Pre-cut squash is typically bigger than ¾", so the roasting and cooking will take a little longer.
It's a personal choice for me to thinly slice the mushrooms and caramelize them. The umami flavor base, for me, elevates the dish. However, you can coarsely the mushrooms instead and just cook until softened with the onion. This takes a fraction of the time - both for prepping and cooking. The tradeoff in the time saved is you lose some of that umami flavor base.
Make the crumble ahead of time, and keep in the refrigerator for up to 1 week.
If making this for a special occasion, make the butternut casserole through the first cooking stage ahead the day before, cool, cover and refrigerate. The following day, bring it to room temperature while you pre-heat the oven, add the crumble, and bake off.
Want more vegetarian and vegan dish ideas? I can help you. I have three newsletters for different topics: 1) Weekly Recipes, 2) Vegetarian Meal Plans, and 3) Monthly Vegetarian Tips for helping you to move to a more vegetarian diet. Choose which newsletters are most relevant to your lifestyle and you'll also get my 5 SECRETS TO FUSS-FREE VEGETARIAN DINNERS.
Butternut Squash Casserole with Apples (Crumble Topping)
Butternut Squash-Apple Filling
- 4 cups peeled and diced butternut squash into ¾" pieces
- 1 tablespoon extra-virgin olive oil
- 2 tablespoons unsalted butter plus more for buttering the pie dish
- 1 cup thinly sliced mushrooms
- 1 cup finely chopped shallots 2 large shallots
- 1 teaspoon kosher salt divided (or ½ teaspoon table salt)
- 2 teaspoons chopped fresh thyme
- ½ teaspoon Better Than Bouillon Vegetable Bouillon Paste, divided (or vegetable broth or water)
- 1 teaspoon balsamic vinegar, I used fig infused balsamic vinegar
- 3 cups thinly sliced apples cored but unpeeled
- 3 tablespoons dried cherries
Do This First
- Preheat the air fryer to 375˚F (190˚C), and generously butter a 9" pie plate or 8" X 8" baking dish.
- Peel and cube the butternut squash. Place in a large bowl and toss the squash with enough olive oil to completely coat the cubes.
- Thinly slice the mushrooms, finely chop the shallots, and slice the apples. Place the apples in a small bowl. You can sprinkle just a little lemon juice on them if you want, so they don't turn brown.
Caramelize the Mushrooms and Shallots
- In a large frying pan, melt the butter over medium-high heat. Add the mushrooms, shallots and ½ teaspoon kosher salt (¼ teaspoon table salt) and cook until the shallots are soft and the mushroom begin to melt into the butter.
- Continue sautéing, only moving the mushrooms around the pan every 5 minutes. They'll start to caramelize and the pan will become dry. A brown fond will begin to show up on the bottom of the pan.
- Once the mushrooms begin to caramelize, but the pan still contains some liquid, add the chopped thyme.
- When the pan is dry, and the fond is apparent, stir in ¼ cup water and ¼ teaspoon Better Than Bouillon paste, and scrape up the bits of fond from the bottom of the pan. Stir in the balsamic vinegar.
- This can take as long as 20 minutes from start to finish.
Air Fry the Butternut Squash
- While the mushrooms caramelize, arrange the butternut squash in the basket of the air fryer so the cubes don't touch each other (or at least not much). Air fry for 12 minutes, or until lightly caramelized.
- Note: If you don't have an air fryer, roast in a 400˚F (204˚C) oven for 15 minutes, or until lightly caramelized.
- Add to the pan with the mushrooms, along with the apples and dried cherries. Toss to mix in the pan so the the caramelized mushrooms coat everything well.
Bake the Butternut Squash Casserole
- Pour the squash filling into the prepared pie plate or baking dish, and add the final ¼ teaspoon Better Than Bouillon paste diluted in ¼ cup water. Cover with foil and bake for 10 minutes.
- Combine all the Crumble ingredients together in a small bowl except the butter and fig jam. Chop the butter into pieces and add to the mixture. Pinch the butter in the mixture until the crumble is coarse, and some chunks of butter are the size of peas. (This can also be done using a pastry blender, or in a small food processor.)
- Gently stir in the fig jam.
- When the squash filling comes out of the oven, remove the foil, scatter the crumble over the top and return to the oven for another 15 minutes, or until the topping is golden brown.
- Serve warm.