A classic side reinvented, this creamy and cheesy Vegan Squash Casserole will steal the show. Summer squash layered with onion, fresh basil, a decadent creamy cheese sauce, and finished with a crispy crust everyone will want to dive into.
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Hey Internet, I used to hate summer squash. Give me a winter squash any day of the week, but I just wasn’t a fan of zucchini or yellow squash. Maybe because I’d only ever had them steamed or soggy.
But zucchini truly shines in this vegan squash casserole recipe. I know, I know, technically yellow squash is typically used in this dish, but I had a TON of zucchini to use up and it’s super cheap around where I live, so zucchini it was.
Luckily, this recipe will work just as well with yellow squash or a mix of the two. Yellow squash is the most authentic to this classic Southern dish, if authenticity is your goal. For that, I’d also use Ritz crackers for the crust instead of Panko, but either will work.
To keep our casserole from being soggy, we’ll saute that squash on the stove top to get as much water out as possible.
Finally, what makes it epic is the creamy and flavorful sauce. Without the sauce, it would just be a bunch of veggies in a baking dish. Ho hum.
Now, I guess this is a side, but my husband and I ate several portions each as a main dish because A.) it was that good and B.) we’re hungry people.
So, let’s get into the recipe.
What You’ll Need
- Summer squash: To cook this delicious casserole, you’ll need some summer squash. Zucchini, yellow squash, or a mix of the two will work fine.
- Onion: Not completely necessary, but adds a lot of flavor and a nice texture.
- Nutritional yeast: I use nutritional yeast in two ways here: to soak up some of the extra liquid and as flavoring. It’s not a super strong flavor, but if you really hate the stuff go ahead and omit it. For reference, I used non-fortified nutritional yeast which is very pale yellow as opposed to the normal super yellow stuff, but either is fine.
- Fresh basil
- Sunflower seeds: To keep things nut-free, the base of the creamy sauce in this dish is raw sunflower seeds which work just as well as cashews and they’re a third of the price. Raw cashews will work just as well though, as will tahini. Peanut butter or almond butter will technically give you a nice creamy sauce, but a much different flavor than intended. Feel free to experiment if you’d like! To make this lower fat, you could also substitute white beans, tofu, or even just some cornstarch to make a thick sauce that’s not fat-based.
- Fresh lemon juice
- Garlic powder / fresh garlic
- Salt and pepper
- Panko bread crumbs: While Ritz crackers are a more traditional crust for squash casserole, I’ve just used Panko bread crumbs because that’s what I have. Use gluten-free panko or rice crumbs for a gluten-free option, or you’re welcome to just top it with a little nutritional yeast.
Tips before you start
For this dish, it’s good to have a large nonstick spot, a strong wooden or non-metal spoon/stirring implement, and a deep large baking dish. I used a 12 x 9 deep baking dish like this one.
When sauteing your onions and zucchini, your pot may not accommodate the sheer mass of zucchini (don’t worry, it cooks down). In that case, start with the onions and half the zucchini, then do another batch with the other half of the zucchini which is what I had to do. For what it’s worth, I used a 4.3qt pot and probably could have fit all 5 pounds of chopped zucchini, but it would have been difficult to stir and get it all to sweat.
Don’t skip sweating the zucchini. If you place it in the oven raw, it will not only take longer to cook, but it will release most of its water in the baking dish which will probably make your casserole very soggy.
How to Make Vegan Squash Casserole
- Preheat the oven to 400 degrees Fahrenheit (205 degrees Celsius).
- In a large nonstick pot, saute the onion on high heat for about 2-3 minutes until it starts to soften. You may use a bit of high heat neutral oil (soybean, grapeseed, etc.) if you like, or just splash a little water in if things start to stick, about a tablespoon or two at a time.
- If you’re doing it in 2 batches, add half the zucchini now and cook on high heat for about 6-7 minutes, stirring frequently. The zucchini should shrink a bit and the water should evaporate during that process. Transfer the zucchini and onions to the bottom of a large, deep baking dish and start the next batch of zucchini, cooking again for 6-7 minutes and stirring frequently. Use your cooking implement to evenly distribute the zucchini and onion in the dish.
- While it cooks, blend the sunflower seeds, water, lemon juice, garlic powder (or peeled cloves), salt, and black pepper until smooth and creamy.
- Pour half of the sauce over the zucchini, spreading it evenly with a spatula. Sprinkle on the chopped basil and half of the nutritional yeast.
- Try to evenly distribute the rest of the zucchini, then pour on the rest of the sauce, spreading it once more with the spatula. Add the remaining nutritional yeast, and then sprinkle on the panko. If you wish, give it a little spray of oil on top (to help it brown), but not necessary at all.
- Bake uncovered for 20-24 minutes, until the top is lightly browned and the sauce is bubbling a little bit.
- Let it rest for 5-10 minutes before serving--the sauce will thicken a little bit.
- Serve hot and enjoy!
- Refrigerate leftovers in an airtight container for up to 3 days.
More delicious vegan side dishes
Side dishes get a bad rap, and yet they’re a lot of peoples’ favorites at Thanksgiving--I know they’re my favorite and it’s been that way ever since I was a kid.
If you liked my vegan squash casserole, you may also like:
- Vegan Elote
- Apple Brussels Sprouts
- Watermelon Salad with Homemade Vegan Feta
- Vegan Italian Salad
- Vegan Creamed Kale
- Roasted Asparagus with Vegan Hollandaise Sauce
- Vegan Mashed Potatoes with Mushroom Gravy
- Vegan Garlic Bread
I hope you love this recipe as much as I do. Mr. Zardyplants loves it too. He and I ate the whole pan as a meal, hah!
This vegan squash casserole is:
- Light yet satisfying
- And perfect for a quick and easy side for dinner, but impressive enough to serve guests or bring to a BBQ or potluck!
Let me know in the comments below if you make this recipe or tag me @Zardyplants on Instagram so I can see your beautiful recreations! If you tag me on IG, I will share your post in my stories :)
Also, one quick request: if you love how this recipe looks or tastes, please leave me a 5-star rating and a nice comment–ratings help more people find my recipes which helps me keep providing them! Thank you!