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Zucchini Yellow Squash and Quinoa Casserole

4.53 from 21 votes
1 hour 30 minutes
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Zucchini, Yellow Squash and Quinoa Casserole is a delicious way to use a summer bounty of zucchini and yellow squash either as a side dish or hearty meatless meal!  With a delightfully creamy texture, the goodness and protein of quinoa, the crunchy topping, it’s worth turning your oven on for!

Photo of Zucchini, Yellow Squash and Quinoa Casserole in white baking dish with some removed to show inside of casserole.

The inspiration behind this recipe:

As it is with any season, when summer rolls around, I can’t wait to make all the tried and true recipes from prior summers.  My Very Veggie Gazpacho is one of the first I reach for and my Spicy Black-Eyed Pea Salad is a close second.

However, if you’re anything like me, you’re always on the hunt for new zucchini and yellow squash recipes!

Every summer, we head up to Wisconsin over the July 4th holiday and this year was no exception.  In a way, it’s a really bad time to leave for a vacation because our garden starts to explode just before we leave.

I needed to find a way to use all the beautiful zucchini and yellow squash you see here and this Zucchini, Yellow Squash and Quinoa Casserole was born!

How to make Zucchini, Yellow Squash and Quinoa Casserole:

  • Start with approximately three pounds of zucchini and yellow squash.  Use even amounts of each or more of one and less of the other.  Either way, it works!
Photo of zucchini and yellow squash in white colander on white background.
  • Slice the squash approximately 1/4-inch thick.
Photo of sliced zucchini and yellow squash in white colander on white background.
  • Saute the zucchini and yellow squash with onion until it has softened.  Never boil zucchini and yellow squash as some recipes call for!  The delicate flavor of these two vegetables will go right down the drain!
Photo of zucchini and yellow squash being sauteed in skillet with white spoon.
  • Combine the squash with cooked quinoa, green chiles, cheese, sour cream, mayonnaise and a couple of eggs.
  • Top with a combination of breadcrumbs, cheese and butter!
  • Then bake!
Photo of Zucchini, Yellow Squash and Quinoa Casserole in white baking dish before being served.
Photo of baked Zucchini, Yellow Squash and Quinoa Casserole on white wood background with white serving spoon and quinoa scattered about.

With a delightfully creamy texture, the goodness and protein of quinoa, the crunchy topping, Zucchini, Yellow Squash and Quinoa Casserole is worth turning your oven on for!

Close-up photo of Zucchini, Yellow Squash and Quinoa Casserole with some served to show interior.

More vegetarian casseroles you might like:

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Zucchini, Yellow Squash and Quinoa Casserole - Hero shot of casserole in white baking dish with some removed and serving spoon resting on the side of the dish

Zucchini Yellow Squash and Quinoa Casserole

4.53 from 21 votes

Click to Rate!

By: Carol | From A Chef’s Kitchen
Zucchini, Yellow Squash and Quinoa Casserole is a delicious way to use a summer bounty of zucchini and yellow squash either as a side dish or hearty meatless meal!  With a delightfully creamy texture, the goodness and protein of quinoa, the crunchy topping, it's worth turning your oven on for!
PRINT RECIPE PIN RECIPE TEXT INGREDIENTS TO PHONE SAVE RECIPE
Prep Time 15 minutes
Cook Time 1 hour 15 minutes
Total Time 1 hour 30 minutes
Course Vegetarian / Vegan Entrees
Cuisine Southwestern / Mexican
Servings 8
Calories 527 kcal

Equipment

Ingredients
  

  • Cooking spray - or oil for baking pan
  • 2 tablespoons canola oil
  • 4 tablespoons butter - (1/2 stick) divided
  • 1 medium onion - chopped
  • 1 1/2 pounds zucchini - sliced into 1/4-inch slices
  • 1 1/2 pounds yellow squash - sliced into 1/4-inch slices
  • 4 cloves garlic - minced
  • 2 cans (4-ounce each) diced green chiles - hot or mild, drained
  • 3 cups cooked quinoa
  • Salt and freshly ground black pepper - to taste
  • 2 cups shredded white Cheddar cheese - or Monterey Jack cheese
  • 3/4 cup sour cream
  • 3/4 cup mayonnaise
  • 2 large eggs
  • 1 cup panko breadcrumbs
  • 1/2 cup freshly grated Parmesan cheese - or Asiago cheese

Instructions
 

  • Preheat oven to 350 degrees. Spray a 13 x 9-inch baking dish with cooking spray or rub lightly with oil. Set aside.
  • Heat oil and 2 tablespoons butter in a large skillet or saute pan over medium-high heat. Add the onion, reduce heat to medium and cook 5-6 minutes or until beginning to soften.
  • Add the zucchini and yellow squash. Continue cooking over medium heat for another 5-6 minutes or until zucchini and yellow squash begin to soften.
  • Add garlic and cook 15 seconds or until fragrant. Let cool.
  • Transfer cooled vegetables to a large bowl. Add green chiles, quinoa and Cheddar or Monterey Jack cheese. Season to taste with salt and black pepper.
  • Combine sour cream, mayonnaise and eggs in a small bowl. Add to vegetable, quinoa and cheese mixture.
  • Transfer to the prepared baking dish.
  • Combine remaining butter, panko breadcrumbs and Parmesan or Asiago cheese in a small bowl.
  • Evenly sprinkle the breadcrumb mixture over the top.
  • Bake uncovered for 45-50 minutes or until golden brown and set.

Notes

MAKE AHEAD: Casserole may be made ahead up to the point of adding the breadcrumb and cheese combination. Add breadcrumb and cheese combination when ready to bake.
FREEZER-FRIENDLY:  Freeze before or after baking for 1-2 months.  Thaw in the refrigerator.  Reheat in the oven at 350 degrees.

Nutrition

Serving: 1 | Calories: 527kcal | Carbohydrates: 30g | Protein: 18g | Fat: 38g | Saturated Fat: 12g | Polyunsaturated Fat: 12g | Monounsaturated Fat: 10g | Trans Fat: 1g | Cholesterol: 101mg | Sodium: 521mg | Potassium: 691mg | Fiber: 4g | Sugar: 7g | Vitamin A: 904IU | Vitamin C: 31mg | Calcium: 371mg | Iron: 2mg

These are estimated values generated from a nutritional database using unbranded products. Please do your own research with the products you’re using if you have a serious health issue or are following a specific diet.

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Recipe Rating




17 Comments

  1. 5 stars
    New favorite healthy squash casserole! In case anyone wants conversion measurements, 1 1/2 lbs of squash is roughly equivalent to 3-4 cups of cut-up squash.

    Also, because I have kids, I decreased the green chiles to one small can instead of two. Still, with the one can hidden in the 9×13 casserole dish, my 6 yr. old couldn’t eat it due to the spiciness of it (I completely disagreed with her, lol). My 8 yr. old didn’t mind it though. So, for young kids, I’d skip it unless they’re used to mild heat.

    Reply

    1. Thanks so much for your question! I have not tried it so I can’t say for sure but you should be able to. I would definitely go with full-fat Greek yogurt. If you try it please let me know how it worked. Thanks so very much!

      Reply

  3. Hello,
    Love your recipes and this looks delicious! Quinoa is not a big hit with my family. Do you think the recipe will work if I swap the quinoa out for rice?

    Reply

    1. Hi, Lori, Thanks so much for your question and your kind words! Swapping out the quinoa for rice should work just fine. Thanks again and hope everyone enjoys!!

      Reply

  4. I just made this and it is delicious! I am a vegan so I made it with Hellmann’s vegan mayonaise and Tofutti’s vegan sour cream. I did use two eggs but I buy eggs from pasture raised chickens…so no problem. I also used gluten free bread crumbs. Oh, and Daiya vegan cheddar cheese and pepperjack style cheese. So, it was a lot healthier with very little cholesterol. I used freshly picked summer yellow squash and zucchini and rainbow quinoa. It is absolutely delicious! I have so much I can’t eat it all by myself. Can I freeze some?

    Reply

    1. Hi, Susan, Thanks so very much and so glad you enjoyed! I love how you made this so super-close to vegan as it appears vegans are interested in this recipe. When I made it the first time, I froze it but I was using all regular products and it worked fine. I think it will be fine frozen but you may want to reheat in a conventional oven. Conventional ovens have a way of “fixing” a lot of things. Thanks again!

      Reply

      1. Thanks for your reply. I will eat as much as I can but it’s a lot of food and unfortunately at this time with the pandemic/shamdemic…lol…no one would want someone else’s food. I will clarify that while it’s not strictly vegan since I did use eggs, I stopped eating meat and dairy for ethical reasons. Health is a secondary benefit. So, as long as the chickens are ☺, so am I. I used some of the vegan cheddar cheese with the breadcrumbs on top at the end instead of parmesan/asiago cheese. Anyway, thanks for the recipe. I will make it in the future when there will be more than just me eating.😀

  5. Made this yesterday and it was delicious. Didn’t add the bread crumbs but going to next time for crunch as you say. Instead of half mayo, could I use all sour cream? I have a friend who is allergic to mayo.
    Thanks again for the good recipe

    Reply

    1. Hi, Jan, Thanks so much and glad you enjoyed! You probably could do all sour cream although I haven’t made it that way. Is there a vegan mayonnaise or mayonnaise-like product that she uses? You could substitute that product. Thanks again!!

      Reply

      2. Hi, Chris, The category is actually Vegetarian / Vegan (Vegetarian –slash– Vegan) so includes both. I don’t have a separate category for vegan recipes because quite often it’s very simple to make something vegan with vegan products.

      3. Your recipe comes up in the top four “vegan” squash casserole. I thought the same thing until I realized it’s the search engine not and not your mistake.