This creamy Zucchini Casserole gives humble squash the star treatment! Thinly sliced zucchini is tossed in a cheesy, garlicky cream sauce, then baked beneath a crown of golden, crispy breadcrumbs for a crowd-pleasing side dish.

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Why You’ll Love This Cheesy Zucchini Casserole Recipe
- A Fancier Way to Enjoy Zucchini. While you might think of zucchini most often as a straight-forward side dish (like Easy Sautéed Zucchini or Roasted Zucchini) this recipe (and Zucchini Pie) proves that when you give it the cheesy holiday treatment usually reserved for Healthy Green Bean Casserole, delicious things happen.
- A Crowd-Pleaser (And Crowd Feeder). This old fashioned zucchini casserole recipe yields 10 servings and it’s always a hit! The sauce is herby and creamy, but light enough to where it doesn’t feel heavy; the buttery panko topping adds pleasing textural contrast
- Uses LOTS of Zucchini. This casserole uses a full two pounds of zucchini, making it an excellent thing to do with the extra squash you will inevitably have on your hands in the summer if you’re a gardener. (Maybe with Healthy Zucchini Muffins and Zucchini Brownies for dessert?)

5 Star Review
“Outstanding, well written and wonderful suggestions. Shared it with a large family group and they begged for more!”
— Bob —
How to Make Zucchini Casserole
The Ingredients
- Zucchini. Often overlooked for the starring role, zucchini makes a fantastic base for this casserole. It becomes tender and soaks up the other flavors while it bakes in the oven. Use you zucchini abundance for creamy Zucchini Soup next!
- Broth. Adds liquid and flavor to the casserole filling. You can use chicken or vegetable broth here.
- Milk. I used 1% milk, but feel free to use whatever you have on hand.
- Plain Greek Yogurt. Whole milk Greek yogurt is the right choice here rather than heavy cream. It adds richness and a subtle tanginess and won’t curdle when heated.
- Cheese. I used both sharp cheddar cheese and Parmesan for the ultimate cheesy combo. The sharp cheddar is bold and deliciously melty, and the Parmesan adds a salty, nutty flavor to the filling and topping.
- Fresh Thyme. A delicious, fresh, herby complement to the creamy casserole filling. You can also swap 1/3 the amount of dried thyme for fresh thyme.
- Panko. Combined with Parmesan cheese and melted butter, panko bread crumbs create an exceptionally crispy and scrumptious casserole topping.
The Directions

- Prep. Slice the zucchini, then place it in a colander. Toss the zucchini with salt and let it drain.

- Cook the Onion. Sauté in a Dutch oven or high-rimmed skillet.

- Add the Flour. Stir so it coats the onions.

- Add the Liquid. Pour in the broth and milk. Let cook until the sauce thickens, then remove it from the heat.

- Dry the Zucchini. Pat it completely dry with paper towels or a clean kitchen towel.

- Make It Creamy. Stir the yogurt into the onion mixture.

- Add the Cheddar. Stir to melt it into the sauce.

- Stir in the Parmesan. Add the thyme too.

- Fold in the Zucchini. Add the zucchini in small amounts, stirring frequently.

- Add Panko. Stir in part of the panko, then transfer the mixture to a baking dish.

- Make the Topping. Melt the remaining butter, then stir in the remaining panko and Parmesan. Sprinkle the mixture over the top of the casserole.

- Finish. Bake zucchini casserole at 400 degrees F for 30 to 35 minutes. Let rest for a few minutes, then ENJOY!
Recipe Variations
- Use Zucchini and Yellow Squash. Take note from this Squash Casserole, and add some yellow summer squash in place of part of the zucchini.
- Add Ground Meat. Sauté 1 pound of lean ground beef, ground chicken, or ground turkey. Stir into the sauce with the zucchini slices.
- Add Sausage. Sauté loose regular sausage or turkey sausage. Stir into the sauce with the zucchini slices. You can also thinly slice cooked sausage links, then add these with the zucchini.
- Make It Bacon-y. Add cooked, crumbled Baked Bacon or Air Fryer Bacon to your sauce and on top.

What to Serve with Zucchini Casserole
- Roasted and Grilled Meats. Zucchini casserole is a great holiday side option year-round. Serve it with Thanksgiving Turkey or summery Grilled Pork Tenderloin.
- Salmon. Rich, hearty salmon can stand up to cheesy casseroles. Try Baked Salmon, Grilled Salmon, or Air Fryer Salmon.
- Chicken. Make it fancy with Bacon Wrapped Chicken Breast or keep it simple with Air Fryer Chicken Thighs.
- Pork. Breaded Pork Chops are a classic main dish to pair with a veggie casserole.
Recipe Tips and Tricks
- Use a Mandoline If You Have One. This is the best way to make sure your zucchini are thinly sliced—and all the same thickness.
- Don’t Skip Salting and Draining. Zucchini has a high water content, and if you don’t find a way to remove the excess before baking it, you’ll end up with a soupy mess. I turned to the method I used for my Zucchini Ravioli: slice the zucchini thinly, sprinkle it with salt to draw out the extra water, then blot dry. This is absolutely ESSENTIAL for the success of this recipe.
- Make the Topping Crispier. For an extra crispy zucchini casserole, place it under the broiler for an additional minute.

Zucchini Casserole
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Ingredients
- 2 pounds small/medium zucchini about 4 or 5 zucchini
- ¾ teaspoon kosher salt divided
- 1 medium yellow onion
- 3 tablespoons unsalted butter divided
- ¼ teaspoon ground black pepper
- 4 cloves garlic minced (about 4 teaspoons)
- ¼ cup all-purpose flour
- 1 cup low-sodium chicken or vegetable broth
- ⅓ cup milk (I used 1%)
- ½ cup whole milk plain Greek yogurt about one (5-ounce) container
- ¾ cup shredded sharp cheddar cheese
- 4 tablespoons finely grated Parmesan divided
- 2 teaspoons chopped fresh thyme leaves or ½ teaspoon dried thyme
- ½ cup Panko breadcrumbs divided
- fresh herbs for serving like fresh parsley or basil, optional
Instructions
- Preheat the oven to 400°F. Coat a 2 ½-quart baking dish (such as an 8×10-inch casserole dish) with nonstick spray.
- Slice the zucchini crosswise into ¼-inch thick rounds (I find this quickest with a mandoline). Place in a large colander. Sprinkle with ½ teaspoon of the salt. Toss to coat the zucchini with the salt, making sure to separate the slices if needed. Place the colander over a large bowl (or in the sink, but don't forget about it and accidentally turn on the water). Let drain at least 20 minutes.
- Cut the onion in half through the stem ends, peel, and cut each half into thin, long strips.
- In a Dutch oven or similar large, sturdy sauté pan, melt 2 tablespoons of the butter over medium heat. Add the onion, black pepper, and remaining ¼ teaspoon salt. Sauté until the onion is beginning to soften and turn translucent, about 5 minutes. Stir in the garlic and let cook 30 seconds.
- Sprinkle the flour over the top. Cook, stirring constantly, for 1 minute, until all of the flour turns golden and no white bits remain.
- Slowly add the broth and milk a few splashes at a time, stirring between each addition to prevent lumps from forming. Increase the heat to medium high. Cook and stir, allowing the sauce to bubble, running a wooden spoon or spatula along the bottom of the pan. Continue cooking and stirring until the sauce reduces and thickens to resemble a very thick, creamy gravy, about 3 to 4 minutes. Remove from the heat.
- Shake the colander to remove as much water as possible, then spread the zucchini onto paper towels or a clean kitchen towel. Blot dry, gently pressing out as much moisture as possible.
- Stir the Greek yogurt into the sauce.
- Add the cheddar cheese a few handfuls at a time, stirring between each addition to ensure it melts smoothly.
- Stir in 2 tablespoons of the Parmesan and the thyme.
- Add the zucchini by handfuls, stirring as you go to coat the slices evenly.
- Stir in ¼ cup panko, then transfer the mixture to the baking dish.
- In a small bowl, melt the remaining 1 tablespoon butter. Add the remaining ¼ cup panko and remaining 2 tablespoons Parmesan, stirring to combine. Sprinkle evenly over the casserole.
- Bake the zucchini casserole until the filling is hot and bubbly and the zucchini is tender but not mushy, 30 to 35 minutes. If desired, switch the oven to broil to brown the top (watch carefully! You will only need a minute or so). Let rest at least 5 minutes, then enjoy.
Notes
- TO STORE: Refrigerate casserole in an airtight storage container for up to 4 days.
- TO REHEAT: Rewarm leftovers in a baking dish in the oven at 350 degrees F or in the microwave.
- Unfortunately, I don’t recommend freezing this casserole, as it will turn mushy and watery when thawed.
Nutrition
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Hi Erin,made this dish for my wife and I for dinner last night,absolutely loved it,tailored it for two and added thin slices of roasted butternut squash to base of the casserole dish,will definitely making it again!😀
Hi Bill! So glad you enjoyed the recipe! Thank you for this kind review!
Made this but downsized it for 2 as there is only one of me. I also added 4 ounces of Mild Italian Sausage. Yum!!!!!!!! This is a keeper. Thanks for posting this casserole.
Hi Kathi! So glad you enjoyed the recipe! Thank you for this kind review and feedback on downsizing it!
We have zucchini coming out of our ears and I was happy to find this recipe. We made last night with some ground turkey and it was delicious! I know I’ll like it w/o the meat also but Cajun hubby has to have meat! LOL.
Hi Luci! So glad you enjoyed the recipe! Thank you for this kind review!
Oreheatb the onion?
Good catch Jan! Fixed it!
Do you think this would work with dairy free yogurt and vegan cheese? My husband can’t eat dairy but I think this would be a great dinner item. Thanks! Thank
Hi Jenn, maybe? I’ve only tested the recipe as written, so I can be sure how well the cheese and yogurt would work out. If you decide to experiment, I’d love to know how it goes!
I tried this recipe, b it made it into a main dish by adding cut up chicken, and sautéing it with the onions etc.
We really enjoyed this recipe a lot! Very delicious way to use zucchini!!!!
Thanks for another great recipe!
Hi Faith! So glad you enjoy the recipe! Thank you for this kind review!
Outstanding, well written and wonderful suggestions. Shared it with a large family group and they begged for more! I did not have Greek yogurt, subed sour cream with a squeeze of lemon on the second making, tasted the same, so very forgiving.
Hi Bob! So glad you enjoyed the recipe! Thank you for this kind review!
Very soupy,bland needs more substance. The casserole needs spice and something that helps all the water from the zucchini that needs absorbing this might work if the zucchini was coated with something that could capture the moisture from the dish.
I’m sorry to hear the recipe wasn’t to your taste, Debra. I know it’s disappointing to try a new recipe and not enjoy it. I (and many other readers) have enjoyed it, so I really wish they would’ve been a hit for you too!
My wife has injured her hand and thus is unable to do the cooking and other kitchen opportunities thus the husband has taking over the duties and is grateful for the many ideas you offer to change up the routine meals.
Sorry to hear that, but glad you are enjoying the ideas!
We loved this casserole! We made ourselves stop at one serving so that we could have it for a second meal — just as good leftover. Now, I’m making it again: for the second time in one week. I added beef to make it a one-dish meal for non-vegetarians. Thanks!
So glad to hear, thank you Sharon!
this is u nder gluten free and flour is gluten!!!
Hi Terri, thank you for pointing that out! When a recipe is super easy to modify, sometimes we put it under this category. So for example, for this one, all of the main ingredients are gluten-free. You could use all purpose flour 1:1 substitute and GF Panko breadcrumbs. Hope this helps!
I really enjoyed this zucchini casserole. At first I was afraid that it would have an overwhelming zucchini flavor, but it didn’t. Although, it did have a ton of flavor! The onions added a nice crunchy texture. And the cheese was the icing on the cake.
So glad you enjoyed it, Bonnie! Thank you!
Always looking for new ways to prepare zucchini. I really liked this one, and it was so quick to assemble! The casserole is soft and cakey (totally a word), it was bursting with flavor. Thank you for this recipe.
So glad you enjoyed it, Mildred!
I just want to say how delicious this dish was. I made this today and I can’t stop eating it. Everything went well together. Served it with BBQ glazed chicken, roasted potatoes, and homemade soft dinner rolls.
Thank you so much, Leslie!
As a veteran vegetable gardener I have had occasion to make a lot of zucchini recipes; pickles, breads, casseroles, etc. There are lots of yummy ways to prepare/eat this squash but I must say this is the BEST ZUCCHINI CASSEROLE I HAVE EVER MADE!! The addition of the plain Greek yogurt to the sauce makes the taste so fresh and piquant. I made this exactly as written except I mistakenly used salted butter rather than unsalted. l used two large yellow zucchinis from my garden and they were fabulous. Thanks Erin for such an unusual take on zucchini casserole!
Makes me so happy to hear, thank you Lynette!