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Vegan Squash Casserole

  • Author: Liz Madsen
  • Total Time: 45 minutes
  • Yield: 12 cups 1x
  • Diet: Vegan


A classic side reinvented, this creamy and cheesy Vegan Squash Casserole will steal the show. This summer squash is layered with flavor!


Units Scale

Squash Casserole

  • 1 medium to large sweet onion (or any onion), sliced
  • 4-5 pounds (about 6 medium) zucchini or yellow squash, sliced in 1/4 inch rounds (see note 1)
  • 1/4 cup packed fresh basil leaves, chopped
  • 1/4 cup nutritional yeast (see note 2)
  • 3 tbsp panko bread crumbs (use gluten-free panko if needed) (see note 3)

Creamy Sauce

  • 1 1/4 cups raw sunflower seeds (see note 4)
  • 1 1/3 cups water
  • Juice of 1 small lemon
  • 2 teaspoons garlic powder or 2-3 cloves garlic, peeled
  • 1 1/2 teaspoons sea salt (or less, to taste)
  • 1/2 teaspoon freshly cracked black pepper


  1. Equipment: 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.
  2. Note: 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.
  3. Another note: 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.
  4. Prep: Preheat the oven to 400 degrees Fahrenheit (205 degrees Celsius).
  5. Saute onion: 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.
  6. Add the zucchini: 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.
  7. Make the sauce: While it cooks, blend the sunflower seeds, water, lemon juice, garlic powder (or peeled cloves), salt, and black pepper until smooth and creamy.
  8. Add half the sauce: 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.
  9. Add the rest of the zucchini: 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.
  10. Bake: Bake uncovered for 20-24 minutes, until the top is lightly browned and the sauce is bubbling a little bit.
  11. Rest: Let it rest for 5-10 minutes before serving--the sauce will thicken a little bit.
  12. Serve hot and enjoy!
  13. Store: Refrigerate leftovers in an airtight container for up to 3 days.


  • Note 1: To cook this delicious casserole, you’ll need some summer squash. Zucchini, yellow squash, or a mix of the two will work fine.
  • Note 2: 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.
  • Note 3: 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.
  • Note 4: 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.
  • Prep Time: 10 minutes
  • Cook Time: 35 minutes
  • Category: Entree, Side
  • Method: Baking
  • Cuisine: American

Keywords: Vegan, Oil-Free, Nut-Free, Soy-Free, Sugar-Free, Can Be Gluten-Free, Zucchini Casserole, Vegan Zucchini Casserole