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This easy, cheesy baked zucchini casserole recipe is perfect for using extra summer produce! Also called zucchini gratin, this dish uses simple ingredients and only takes 10 minutes of hands-on effort. And just like yellow squash casserole, it creates tender slices in a rich, creamy sauce.
As we head into August, I know I’m not the only one with more zucchini than I know what to do with. Even though I don’t have a garden, I still have a zucchini problem: I just couldn’t resist buying way too much at the farmers’ market. Well, zucchini casserole recipes are the perfect way to use up a lot of it at once!
The only thing is, I struggled with the name for this dish. Cheesy zucchini gratin? Baked zucchini casserole? Healthy zucchini bake? I couldn’t decide, so I’m using the names interchangeably.
If you still have leftover veggies, try more zucchini recipes next, like zucchini fries, zucchini chips, or zucchini noodle salad.
Why You’ll Love This Zucchini Casserole Recipe
- Summery veggie flavor
- Creamy cheese sauce
- Made with basic ingredients
- 10 minutes to prep
- No panko breadcrumbs or other grains
- Naturally keto-friendly, gluten-free, and low carb side dish
- Loaded with veggies and fiber!
Ingredients & Substitutions
This section explains how to choose the best ingredients for zucchini squash casserole, what each one does in the recipe, and substitution options. For measurements, see the recipe card below.
- Zucchini – Use 3 medium zucchini with firm flesh and no nicks. Yellow squash would work equally well if that’s what you have on hand. Either way, slice the summer squash into thin rounds.
- Salt & Pepper
- Swiss Gruyere Shredded Cheese – I used a pre-mixed shredded blend, but you can also shred Swiss and Gruyere cheese separately yourself and mix them together. Alternatively, any shredded sharp cheese, such as cheddar cheese, will work as well. Harder cheeses, like parmesan cheese, might not melt as smoothly.
- Brie Cheese – Helps the sauce thicken and get creamy. You could also substitute cream cheese instead.
- Heavy Cream – Thins out the sauce, but not too much. I recommend using cream for the thickest sauce possible. Milk, half and half, almond milk, or coconut milk can work, but you’d need to use less so that the dish doesn’t get too watery.
- Butter – Adds richness to the sauce. I use grass-fed butter, but any unsalted variety will work.
- Garlic – Use minced or crushed, fresh or from a jar.
- Italian Seasoning – Use a store-bought mix or make homemade Italian seasoning in minutes.
VARIATION: Add onion!
You can saute some diced onions (or shallots), and stir them into the cheese sauce mixture, or slice the onion into rings and layer them with the zucchini slices.
How To Make Zucchini Casserole
This section shows how to make zucchini gratin, with step-by-step photos and details about the technique, to help you visualize it. For full instructions, including amounts and temperatures, see the recipe card below.
- Drain zucchini. Place the zucchini slices in a colander, sprinkle generously with salt (3/4 teaspoon salt is a good amount), and drain over the sink for 45 minutes. (Doing this prevents a watery casserole!) Pat dry.
- Arrange. Arrange the zucchini slices in rows in a baking dish, sprinkling half of the shredded cheese between each row. Season with pepper. (No salt needed here, as we already salted the slices in step 1.)
- Make sauce. Heat brie, cream, butter, and garlic in a saucepan over medium-low heat. Stir frequently, until cheese melts and sauce is smooth. (Alternatively, you can heat the ingredients in a bowl in the microwave and stir every 20-30 seconds, until melted.) Add salt to taste. Pour the sauce evenly over the zucchini in the baking dish.
- Add more cheese. Sprinkle more shredded cheese on top, followed by Italian seasoning.
- Bake. Place the zucchini casserole in the oven, until the zucchini is soft and the cheese on top is dark golden brown.
Tips For The Best Zucchini Casserole
To make sure your au gratin zucchini turns out perfect, keep these tips in mind.
- Don’t skip the salting and draining step. Otherwise this recipe for zucchini casserole will stay too watery, because the zucchini will release water as it cooks. Salting beforehand removes some of the water in advance.
- Try different cheeses (or herbs). Fresh herbs such as rosemary would also taste delicious with this baked zucchini casserole recipe.
- If sauce stays watery, bake longer. Cover the top of the casserole, lower the temperature to 350 degrees F, and bake for 10-20 minutes more, until the sauce thickens.
- Add a crunchy topping, if desired. Use panko bread crumbs if you want, or crushed pork rinds for a low carb alternative.
Cover leftovers in an airtight container and store in the refrigerator for up to 3 days.
Can You Freeze Zucchini Casserole?
Avoid freezing this zucchini casserole recipe, as the texture will change too much after thawing.
Heat in a microwave or 350 degree F oven until warm.
What To Serve With Zucchini Casserole
This dish pairs well with most proteins, but especially Italian dishes! Try these mains:
More Cheesy Veggie Casserole Recipes
If you like a baked zucchini casserole recipe, you’ll enjoy these cheesy favorites too!
Tools To Make Zucchini Gratin
- Colander – A must-have for draining wet vegetables like zucchini.
- Stoneware Dish – The perfect size for this zucchini casserole.
- Small Saucepan – For making the sauce.
Baked Zucchini Casserole Recipe
Zucchini Casserole (Easy & Cheesy!)
This easy zucchini gratin is a baked cheesy zucchini casserole recipe everyone will love! Only 10 minutes prep time & simple ingredients.
Recipe VideoTap on the image below to watch the video.
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Tap on the times in the instructions below to start a kitchen timer while you cook.
Toss the zucchini slices with sea salt. Place into a colander and set over the sink to drain for 45 minutes. Pat dry at the end.
Preheat the oven to 400 degrees F (204 degrees C).
In a small 1.5 quart (1.5 L) casserole dish, arrange the zucchini slices in several overlapping rows, sprinkle lightly with shredded cheese. Add another row and more shredded cheese. Continue alternating zucchini and cheese until you fill the entire baking dish. You’ll use about 3/4 cup (half of the total) cheese altogether. Season lightly with black pepper.
Combine the brie, cream, butter, and garlic in a small saucepan. Heat for a few minutes on the stove over low to medium-low heat, stirring frequently, until the cheese melts and the mixture is smooth. If desired, add sea salt to taste. Pour the mixture evenly over the zucchini.
Sprinkle the remaining 3/4 cup shredded cheese blend on top. Top with Italian seasoning.
Bake for about 20-25 minutes, until the cheese on top is dark golden brown and the zucchini is soft.
Last Step: Leave A Rating!
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Serving size: 1/6 of entire pan
Nutrition facts are provided as a courtesy. Have questions about calculations or why you got a different result? Please see our nutrition policy.
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This was delicious! I added shrimp on top of the zucchini, then the shredded cheese, topped with chopped bacon.
What could be substituted for the brie?
Wholesome Yum D0
Hi Julie, You can omit the brie or use another creamy cheese.
Could you use jarred alfredo sauce instead of the melted mixture?
Wholesome Yum D0
Hi Susan, That could work I would just make sure the sauce is low in carbs.
Can I substitute the Brie with Cream Cheese?
Maya | Wholesome Yum0
Hi Teresa, Yes, that should work and also sounds delicious!
This was a wonderful dish! A true crowd pleaser👏 I used herbed Gouda cheese as that was what I had on hand and it was really delicious. I’ll definitely add this recipe to my permanent rotation.
Yum – great side dish. I made this for a family gathering this week and everyone was so impressed!
This is such an amazing side dish!! Everyone was really impressed!
So cheesy and delicious! I love that brie cheese is incorporated into this recipe, it’s my favorite!
Looks delicious, but is it Gluten Free?
Wholesome Yum D0
Hi Mary Lou, Yes, all my recipes are gluten free.
I picked this recipe because it was fast prep. It wasn’t so fast. Melting the ingredients in the pot alone took 10 minutes. Slicing and layering the zucchini and cheese took another 10. Prep took me 30 minutes, including grating cheese and slicing the sides off the brie. I served a group of six this dish, and they all loved it! So it was definitely worth the 30 minute prep.
Can you make this ahead of time?
Wholesome Yum D0
Hi Lacy, Yes, you can make this ahead of time and reheat.
Can it be made ahead of time?
Wholesome Yum D0
Hi Marzie, Yes, you can make this ahead of time and reheat.
JANET LYNN HUTCHINSON0
So glad to find a zucchini recipe that doesn’t use parm. Don’t misunderstand me. I like parmesan, but I would like a different flavor profile with zucchini. Can’t wait to try this.
Did the draining and salting but it was still soggy. The Gruyère/Swiss is such a strong flavor that you can’t taste the Brie.These are all flavors I like but the recipe was disappointing.
I made this recipe exactly as is for my whole family on Mother’s Day and they loved it so much that my aunt texted this week to say that she and my grandmother were requesting I bring it to Thanksgiving. It’s such an easy dish to make, I’m happy to!
I love this recipe!!! Actually the whole family loves it. I didn’t have brie on hand so I sued laughing cow cheese and it worked out perfect.
Question about the brie. I’m guessing it’s the block form? do you grate it or shred it? I thought brie was a softer cheese. I haven’t bought brie in years, so not sure what to buy. I also see double cream and triple cream.
This recipe looks awesome.
Sorry for so many questions
Wholesome Yum M0
Hi Anne, Brie can be purchased in a round of wedge form. It is a soft cheese, so grating is not necessary. It will be melted down in the cheese sauce that gets poured over the zucchini. I did not use a double or triple cream brie, but all options would work in this recipe.
First, I sauteed the onion, garlic, and then the zucchini. Because I want my zucchini cooked a bit more.
Then I added the other ingredients except for the last 3/4 cup of cheese. I substituted half and half for the heavy cream and a mix of shredded italian cheeses. I did this because I’m feeling lazy and only wanted to clean one pan.
I know, I know, it’s not the recipe. And I dislike reading reviews that say this was a good recipe BUT I completely changed it. With that said, your ingredients were awesome…in short YUMMO!
Heather- I’m going to use 1/2 & 1/2 also and whatever cheese I have in the fridge. Going to sub cream cheese for the brie.
This has such a great flavor! Even though I dried out the zucchini (salted and let it sit for 45 min patting along the way), the bottom of the dish was quite soupy and not as thick as in the photos. I used a larger dish and maybe that was part of it.
I have to take this time to compliment your sweeteners (granulated, powdered and brown). They are the best out there! No aftertaste and my family can’t tell the difference.
Should the rosemary be chopped or should I just throw a few twigs on top before baking?
Wholesome Yum M0
Hi Kazy, If you would like to add rosemary, I would remove it from the stem and finely chop it.
I was wondering if dehydrating the Zucchini sliced and using them in the casserole would be helpful with the “soggy” or “too runny” comments?
Kind of the box scalloped potato method but way more healthy 🙂
I am going to try it tomorrow (wish me luck).
Wholesome Yum M0
Hi Kaite, I’m not sure, I haven’t tried dehydrating the zucchini. Please share with us how it turns out!!
It turned out great…I didn’t have enough time to completely dehydrate the zucchini slices but I think it helps the texture. Fabulous recipe, very good pairing of cheeses.
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