Healthy, simple, and fabulous, this Zucchini and Squash Casserole is the best low-carb recipe for Summer squash! Yellow squash and zucchini are baked in the oven to perfection with a crispy crust made from Parmesan cheese and breadcrumbs. This easy casserole is amazing for Summer picnics and potlucks, and makes the perfect side dish for any holiday dinner!
Zucchini and Squash Casserole Recipe
Zucchini and yellow squash are some of the overlooked vegetables that somehow magically reappear during the summer months and at a Thanksgiving table.
I first discovered my love of cooking with this delightful combo when Cohl started coming home with enormous bags full of fresh summer produce from a fellow dentist at his office.
After making a few batches of this Sauteed Zucchini and Squash, I started to run out of new recipe ideas.
And then one week he came home and the bag was packed to the brim with yellow summer squash and zucchini.
It would be a sin to let them all go bad, so I had to brainstorm a new summer recipe.
Squash casserole has always been one of my favorite summertime side dishes.
But this time it would be a healthier version that was still simple to make and baked in the oven.
Ingredients
Sure, the cheesy and cream-laden squash casseroles taste ah-maaazing, but let’s be real… all of that dairy takes away the incredible flavor of the fresh vegetables!
The ingredients for this zucchini and yellow squash casserole recipe are pretty simple. You probably have most of them in your kitchen already:
- Squash – Feel free to use all yellow squash or all zucchini if that’s what you have. However, the alternating colors are what make this casserole so unique and pretty!
- Olive oil – You can also use any other type of healthy oil that does not have a ton of flavor. Avocado oil, safflower, and sunflower oil will all work equally as well.
- Garlic Powder – The secret ingredient that gives this dish a unique flavor!
- Parmesan cheese – Regular, dairy-filled, Parmesan cheese is best. You can also use a vegan and dairy-free Parmesan cheese.
- Panko Breadcrumbs – You can use regular breadcrumbs or gluten-free breadcrumbs. The taste will be minimally affected.
- Parsley – Not absolutely necessary but makes the casserole really pretty when serving.
Expert Tip: You can substitute with a seasoned breadcrumb mixture, but you will need to make sure to adjust the amount of salt you add!
Preparing Squash for Casserole
To get the Summer squash ready to bake there are a few things to do.
First, you need to slice it into uniform pieces. You can either use a mandoline (if so be very careful with fingers!), or you can thinly slice them by hand.
You want them to be ¼-inch thick. If they end up thicker, it will need to cook longer. If thinner, it will likely be soggy instead of crisp.
Next, sprinkle salt over all of the sliced squash and let sit for 10 minutes. Then wipe away any excess moisture that forms with a paper towel.
This little trick allows the sliced zucchini and squash to release a large amount of the water they retain. It will help you to get a crispy, and not soggy, casserole.
How to Make
As I mentioned previously, this recipe is not only healthy, but it is also extremely easy to make. Here are the steps for how to make a zucchini and squash casserole:
- Layer the zucchini and yellow squash.
Alternate the zucchini and yellow squash in a 9-inch square baking dish. (Steps 1 and 2 above.)
- Sprinkle with remaining salt and pepper.
Lightly season the layered squash (Step 3 above.)
- Whisk together breadcrumbs, Parmesan cheese, and garlic powder.
Then evenly shake it over the zucchini and squash. (Step 4 above.)
- Cover baking dish with aluminum foil and bake in preheated 350° oven for 30 minutes.
It may take a few minutes more if the slices were cut thick, or less time if the slices are thin.
- Broil for 3-5 minutes.
Keep a close eye on it! The topping will crisp up and turn brown quickly.
Meal Prep and Storage
You totally can prep-ahead and have this side dish ready-to-go when you are. This is especially handy when it comes to preparing a healthy casserole for a backyard BBQ, picnic, or Thanksgiving day.
- To Prep-Ahead: Follow all directions but wait to bake until you’re ready to serve. Cover tightly with foil and refrigerate for up to 2 days. Bring to room temperature and bake according to directions.
- To Store: If there happen to be leftovers, store in an airtight container in the refrigerator.
- To Reheat: Preheat your oven to 300°. In an oven-proof dish bake the zucchini and squash for 10-12 minutes or until heated through. You can also broil the casserole again for 1-2 minutes to bring back some of that crunchy topping.
FAQs
Squash releases liquid while cooking. However, there is a trick to prevent this. Before cooking, sprinkle the squash with salt, let it sit for about 10 minutes, then blot it dry.
Yes you can! Zucchini is a member of the squash family, and goes wonderfully in many casserole recipes.
When it comes to Summer squash, no. In fact, leaving the skin on adds a nice color and texture to many dishes.
If your harvest comes in all at one time – squash and zucchini casserole is the answer! You can also sauté squash or roast it in the oven with other vegetables in this Italian Roasted Vegetables recipe.
Expert Tips and Tricks
- Use a mandoline. This gives you the most precise slices so they all cook at a similar rate.
- Sprinkle a little salt to prevent a soggy mess. Let the salted squash sit, then blot dry. The salt releases excess moisture.
- Try out Italian breadcrumbs. Since they’re pre-seasoned and often contain salt, you will have to adjust the other seasoning ingredients.
- Broil it at the end. This gives it a great crunchy topping.
- Use all of one squash – If it’s all you have, either use all zucchini or all yellow squash.
Other Squash Recipes
If you like this Summer squash casserole, make sure to check out these other recipes:
More healthy side dish recipes.
Healthy Summer Squash Casserole
Healthy, simple, and fabulous, this Zucchini and Squash Casserole is the best low-carb recipe for Summer squash! This easy casserole is amazing for Summer picnics and potlucks, and makes the perfect side dish for any holiday dinner!
Ingredients
- 2 lbs. summer squash zucchini and yellow squash, cut into ¼-inch slices
- 2 ½ Tbsp. olive oil
- 1 ¼ tsp. salt divided
- ½ tsp. pepper
- ⅓ cup Parmesan cheese* grated
- ⅓ cup Panko breadcrumbs gluten-free
- ¼ tsp. garlic powder
- 2 Tbsp. fresh parsley finely chopped
Instructions
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Preheat oven to 350 degrees.
-
Cut yellow squash and zucchini into thin, ¼-inch slices.
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Sprinkle ½ teaspoon salt over the zucchini and squash slices. Let sit for 10 minutes and then dab to remove excess moisture with a paper towel.
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Spray a 9-inch square baking dish with non-stick cooking spray.
-
Alternatively, overlap the zucchini and squash in a row. (See pictures.) You should be able to form 4 rows.**
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Drizzle olive oil over the zucchini and squash and then sprinkle with salt and pepper.
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In a small bowl combine Parmesan cheese, breadcrumbs, and garlic powder. Toss to combine and then sprinkle over the zucchini and squash.
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Cover baking dish with aluminum foil and bake in preheated oven for 30 minutes.
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Remove foil and turn heat to a High broil. Broil for an additional 5-7 minutes, or until breadcrumb topping starts to turn a golden brown.
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Serve immediately with fresh parsley and enjoy!
Recipe Video
Recipe Notes
*Can use a vegan Parmesan cheese substitute.
**I like to get small-medium, similarly-sized summer squash so they will be able to fit into four rows easily!
Expert Tips and Tricks
- Use a mandoline. This gives you the most precise slices so they all cook at a similar rate.
- Sprinkle a little salt to prevent to soggy mess. Let the salted squash sit, then blot dry. The salt releases excess moisture.
- Try out Italian breadcrumbs. Since they’re pre-seasoned, you will have to adjust the other seasoning ingredients.
- Broil it at the end. This gives it a great crunchy topping.
- Use all of one squash – If it’s all you have, either use all zucchini or all yellow squash.
Meal Prep and Storage
- To Prep-Ahead: Follow all directions but wait to bake until you’re ready to serve. Cover tightly with foil and refrigerate for up to 2 days. Bring to room temperature and bake according to directions.
- To Store: If there happen to be leftovers, store in an airtight container in the refrigerator.
- To Reheat: Preheat your oven to 300°. In an oven-proof dish bake for 10-12 minutes or until heated through. You can also broil the casserole again for 1-2 minutes to bring back some of that crunchy topping.
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DIANE TINNES says
How much garlic powder do you use? The recipe doesn’t include it in the ingredients.
London says
Hi Diane! So sorry for any confusion. The recipe has been updated with the amount of garlic powder you need 🙂 Thanks for asking!
Karen says
Can you do this in the air fryer
London says
You might be able to, but I have not personally tried it yet, Karen! Would love to know if you do and what you think!
Margaret E Clegg says
Love this recipe idea. With it being almost time to plant our garden, this will be perfect for the PLETHORA of zucchini we’ll have!
London says
It is the perfect thing to do with SO much squash and zucchini! Can’t wait to hear what you think, Margaret!
Judy says
Hi London , this recipe sounds delish , was wondering why the sodium content was so high in this recipe… Is there a way to cut back on the sodium, I’ll still make it & let everyone salt their own ….Thanks for the recipe !!
London says
Hi Judy! Parmesan cheese, breadcrumbs, and the added salt contribute to the somewhat high sodium count. You can definitely decrease the amount of salt added as well as look for a breadcrumb mixture that does not have as much sodium to help decrease it a bit. Would love to hear how it turns out for you!
Jules Shepard says
This recipe is actually on the menu for me this week along with some salmon! Can’t wait to give it a go!
London says
Yay!! Can’t wait to hear what you think, Jules!!
Donna says
This was a big hit at our Christmas Eve dinner! Thanks so much for the recipe!
London says
Yay!! So so happy you and the family enjoyed it, Donna!
Anonymous says
Very good! We’ll make it again 🙂
London says
Yay!! So happy you enjoyed it. Thanks for the comment and rating 🙂
Joyce says
Great flavor, too watery. I made it again but salted the squash slices, let them sit 5 minutes and squeezed them in paper towel. The end result was less watery and more like a casserole.
London says
That’s a great idea to dry them out a bit beforehand. I’ll have to try that next time! Thanks so much for your feedback, Joyce!
Mollie says
Loved this! Thanks for the great recipe!
London says
You’re so welcome, Mollie! So happy you enjoyed it 🙂
Lillian says
Loved this! The second time I made this I forgot the Parmesan cheese. Ugh. However I subbed with mozzarella and Italian breadcrumbs. Almost tasted like pizza…tried it a third time with tomato sauce. It was yum.
Thanks so much for the recipe! My entire family loves it.
London says
Hi Lillian! I absolutely love your idea to add tomato sauce… I bet that was delicious! Thanks so much for the comment 🙂
Savannah says
This looks absolutely delicious! I have to make this ahead of time and I was just wondering if I could go ahead and sprinkle the breadcrumbs and parmesan mixture over the zuchinni and squash and put it in the fridge or should I wait and sprinkle it after I take it out of the fridge and bring it room temperature? Thank you so much! 🙂
London says
Hi Savannah! Yes! You can go ahead and sprinkle the breadcrumbs/parmesan on top of the squash and refrigerate it. Bring the entire casserole to room temp before you bake it for the best results! Hope this helps 🙂