Vegetarian Butternut Squash Casserole with Apples

November 21, 2023 36 Comments

This flavor-packed vegetarian butternut squash casserole includes caramelized mushrooms, shallots, and apples. It's all topped with an oat crumble mixed with a little fig jam for a perfect savory and sweet combination!

This delicious recipe also shares shortcuts, make-ahead tips, and ways to roast butternut squash, and an option for including quinoa for a vegetarian main dish.

Jump to Recipe

Butternut squash and apple crumble with mushrooms in a baking dish.

Want to Save This Recipe?

Enter your email & I'll send it to your inbox. Plus, get great new recipes from me every week!

Want to make this recipe perfectly the first time? I want to help with that. So, check out this Table of Contents to see which sections of this post will help you the most.

Jump to:

❤️ Why you'll love this recipe
🧅 Main Ingredients + Notes
🔪 Recommended Equipment
📝 Instructions Overview
👩‍🍳 How to Prep Butternut Squash
⏰ Tips to Simplify and Save Time
👩‍🍳 Cooking Tips
💡Ideas for Possible Variations
🥬 Make it Vegan
🤩 Leftovers
Vegetarian Butternut Squash Casserole with Apples

I roast up a lot of butternut squash during the fall and early winter months. It makes an excellent savory soup, turns a side salad into a main vegetarian salad entree, and hasselbacked butternut squash is a beautiful, special dinner.

This vegetarian butternut squash casserole recipe is another of my favorite ways to use roasted butternut all through autumn. It's also an excellent side dish for Thanksgiving.

❤️ Why you'll love this recipe

Flavorful. This casserole is a balance of savory and sweet, to satisfy everyone at the table.
Make-ahead. Make it ahead, and rewarm when ready to serve.
Main or side dish. Add cooked quinoa to the casserole and serve it as a cozy weeknight dinner. Or serve as a side dish for the meat lovers at the table.
Thanksgiving dinner. This casserole is a great comfort dish for your holiday table.

🧅 Main Ingredients + Notes

The secret to faster and easier meals often lies in the ingredients. For example, store-bought items and ingredients you make ahead and store in the refrigerator (or freezer) can turn a 60-minute recipe into a 30-minute meal or less.

For all of the ingredients, measurements, and directions, go to the Recipe Card at the bottom of this post.

Butternut Squash Casserole

Butternut squash - since you only need 4 cups, a smaller butternut squash is all you need.
Cremini mushrooms - other mushrooms work well too, such as white mushrooms or shiitake mushrooms. Feel free to use your favorites.
Shallots
Fresh thyme
Vegetable broth - or Better Than Bouillon - Roasted Vegetable Bouillon Paste.
Balsamic vinegar - you don't need much, so you don't need one of the expensive ones. I always have fig balsamic vinegar on hand, and is my favorite for this casserole.
Honeycrisp apples - or other apples suitable for baking, such as Fuji, Pink Lady, or Braeburn apples. Granny Smith apples are too tart for this recipe.
Dried cranberries - or dried cherries.

Crumble Topping

All-purpose flour
Rolled oats - don't use Instant Oats
Brown sugar - purchase or make your own brown sugar!
Fig jam - purchase or make your own spiced fig jam.

Disclosure: This post may contain affiliate links to products and foods I use in my kitchen. This means that at no additional cost to you, I will earn a commission if you click through and make a purchase. To view my entire storefront of recommended kitchen tools and equipment, check out my shop on Amazon.

🔪 Recommended Equipment

Having the right equipment for recipes makes prepping so much easier. If you want more fuss-free prepping and cooking, check out my updated list of favorite kitchen tools and equipment.

Four of the process steps in making a vegetarian butternut squash casserole, with text overlay.

📝 Instructions Overview

Detailed instructions for making this butternut squash dish are in the recipe card below, but here's an overview!

Step 1

Butternut squash. Peel, cube, and air fry the butternut squash. If you don't have an air fryer, roast in a 400˚F oven until tender. The exact amount of time will be dependent on the size of the butternut squash cubes, but a good rule of thumb is 20 - 25 minutes in the oven and around 10 - 12 minutes in the air fryer.

Step 2

Sauté. Prep the mushrooms and shallots, and sauté until lightly caramelized and the pan is dry. Wait until a fond develops on the bottom of the pan, and stir in the broth, balsamic vinegar, and thyme. Be sure to scrape up the fond as you stir everything together, as it's full of savory, umami flavor.

Step 3

Combine. Add the roasted butternut squash, apples, and dried cranberries to the mushrooms and shallots and gently stir together.

Step 4

Bake. Transfer the butternut squash mixture to a casserole dish or deep pie plate. Drizzle additional vegetable broth over the squash, cover, and bake.

Step 5

Crumble. Make the crumble, and spread it over the butternut squash casserole. With the casserole dish still uncovered, bake until the crumble topping turns a golden brown.

👩‍🍳 How to Prep Butternut Squash

Slice off the top and bottom of the squash. If the skin is too tough to do this easily, pop it into the microwave oven for a few minutes to soften the skin.
Stand the squash up on end, and cut it in half lengthwise. Scoop out the seeds and pulp with a spoon.
Lay the squash down flat, and peel it with a vegetable peeler. I prefer to use the Y-shaped peelers for this.
With the cut side of the squash facing down on a cutting board, slice it into ¾" cubes.

Butternut squash and apple crumble casserole in a deep pie dish.

⏰ Tips to Simplify and Save Time

Purchase butternut squash already peeled and diced. If they are cut into large cubes, you may need to cut them a little smaller. The ideal size is ¾".
Coarsely chop pre-sliced mushrooms.
Make the crumble ahead of time, and keep it in the refrigerator for up to 1 week.
Bake the casserole until it's time to add the crumble, cool to room temperature, and cover tightly. Refrigerate for up to 2 days. When ready to finish the dish, bring it to room temperature, add the crumble, and finish baking.

👩‍🍳 Cooking Tips

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, or they won't caramelize. When you're done, the pan should be completely dry, with a nice fond on the bottom.
Covering the casserole with foil for the first part of the baking process is important, 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. When the crumble pieces are smaller, the topping bakes up more like a pie crust than a crumble.

💡Ideas for Possible Variations

Substitute delicata squash or kabocha squash for the butternut, or use sweet potatoes.
Golden raisins, dried figs, and dried cherries all are great in this casserole in place of the dried cranberries.
Tear up dinosaur kale leaves, discarding the central stem, and sauté them in the pan after the mushrooms and shallots caramelize. Or use baby kale.
Add cheese before sliding the casserole into the oven. Gruyere is a great choice, or if you add black beans to make it a main dish, use Monterey Jack cheese.
Turn this vegetarian side dish into a main dish by stirring 1 cup of cooked quinoa into the caramelized mushrooms and shallots (shown below). Alternatively, add 1 cup of cooked black beans. Check this article out for more ideas on increasing the protein content in this butternut squash casserole.
Add pumpkin seeds (pepitas) or roasted pecans for a nutty flavor.

A pan with cooked quinoa stirred into caramelized onion and mushrooms. — *Cooked quinoa stirred into caramelized onions and mushrooms for a butternut squash quinoa casserole.*

🥬 Make it Vegan

Make this a vegan butternut squash casserole by eliminating the crumble topping.

🤩 Leftovers

Store any leftovers in an airtight container and keep in the refrigerator for up to 2 - 3 days. After that, the crumble topping turns soggy.

Want to Save This Recipe?

Enter your email & I'll send it to your inbox. Plus, get great new recipes from me every week!

Top and side view of butternut squash casserole with apples and mushrooms.

4 from 3 votes