This garlic Parmesan zucchini casserole turns a pile of summer squash into a cheesy, comforting side with a crispy, buttery breadcrumb topping. The trick is drying the zucchini well, so every bite bakes up tender and golden instead of watery. It comes together with about 15 minutes of hands-on prep and pairs with almost any main.
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Before You Get Started
A few small things make the difference between a creamy, golden casserole and a soggy one. Keep these in mind before you start.
- Squeeze the zucchini dry. Salt it, let it sit, then wring it out in a dish towel or salad spinner. This is the step that keeps the casserole from turning watery.
- Use cheese that melts well. A blend of mozzarella, sharp cheddar, and Parmesan gives you stretch, flavor, and a crisp top.
- Bake it uncovered. Leaving it open in the oven lets the top brown and crisp while the extra moisture cooks off.
How to Make Zucchini Casserole
This old-fashioned zucchini casserole is the kind of recipe that comes together while the oven preheats.
Step 1: Salt and Drain the Zucchini
Pile the grated zucchini in a colander, sprinkle it with salt, and let it sit for about 10 minutes. The salt pulls out the water that would otherwise leave you with a runny casserole.
Then squeeze it dry: wrap the zucchini in a clean dish towel and wring it out a few times. You will be surprised how much liquid comes out.
⇢ Have a Salad Spinner on hand? A spinner lined with paper towels does a lot of the work, and a reader tip we love is salting the zucchini in the morning and letting it drain all day for an even drier start.
Step 2: Mix the Filling
In a large bowl, stir together the drained zucchini, onion, garlic, eggs, half of the Parmesan, the mozzarella, and the cheddar. The eggs hold everything together as it bakes, so the casserole slices into neat squares instead of falling apart.
Gently press the mixture into a greased baking dish.
⇢ Want a little more kick? A pinch of black pepper or crushed red pepper, or a teaspoon of Italian seasoning, adds warmth to the filling.
Step 3: Bake the Casserole
Bake uncovered for about 20 minutes.
Keeping it uncovered is what lets the surface set and any remaining moisture cook off, instead of steaming in the dish.
Step 4: Add the Crispy Topping
While the casserole bakes, stir together the melted butter, panko breadcrumbs, and remaining Parmesan until the crumbs are evenly coated.
Sprinkle the topping over the casserole and return it to the oven for another 5 to 10 minutes, until the top is deep golden brown and crisp.
⇢ Swap the butter for olive oil. Tossing the breadcrumbs with olive oil instead of melted butter gives the topping a slightly different, savory flavor.
Step 5: Finish and Garnish
Let the casserole rest for a few minutes so it sets up before serving. A scatter of fresh parsley, basil, or thyme, or a squeeze of lemon, brightens up all that cheese.
⇢ Make it with yellow squash. You can use yellow summer squash for some or all of the zucchini, and a handful of shredded carrot is a nice addition too.
easy, delicious and a good low carb veggie dish. I added a heavy splash of hot sauce and some freshly grated nutmeg to balance all the cheese. this recipe is a keeper
– Sheba
How to Serve
This casserole is happiest next to something off the grill in the summer, but it works alongside a holiday ham or roast just as well. It can even stand in as a meatless main with a salad and some crusty bread.
Serve it with:
- Grilled BBQ Chicken Breast
- Grilled Salmon
- Grilled Pork Chops
- Grilled Hamburgers
- Marinated Grilled Shrimp
- Southern Meatloaf
Storage, Reheating, and Freezing
To Store: Keep leftovers in an airtight container in the refrigerator for up to 3 days.
To Reheat: Warm in a 350°F oven just until heated through, or microwave individual servings for 30 to 60 seconds.
To Freeze: You can freeze it, but it isn’t my preference. Zucchini holds a lot of water, so the texture and flavor suffer once it thaws. This one is best enjoyed fresh.
Frequently Asked Questions
How do you keep zucchini casserole from getting watery?
Drying the zucchini is everything here. Salt the grated zucchini and let it sit for about 10 minutes, then wring it out hard in a dish towel or salad spinner before it goes in the bowl. Baking the casserole uncovered also helps any leftover moisture cook off rather than pool in the dish.
What cheese is best for zucchini casserole?
A mix works best: mozzarella for stretch, sharp cheddar for flavor, and Parmesan for that salty, crisp finish. If you’d rather keep it simple, an equal amount of just mozzarella or just cheddar is fine. Monterey Jack, Colby Jack, Pepper Jack, Gruyere, Swiss, and Gouda all melt nicely too.
Can you use yellow squash instead of zucchini?
Yes. Yellow summer squash works in place of some or all of the zucchini with no other changes. It carries a little more water than zucchini, so be especially thorough when you salt and squeeze it dry.
Do you need eggs in this casserole?
The eggs act as a binder, holding the cheese and zucchini together so the casserole slices cleanly instead of falling into a loose pile. They’re worth keeping in, but if you leave them out, expect a softer, more scoopable result.
Do you have to peel the zucchini first?
No need. The skin is thin and tender once baked, and it adds color and a little extra nutrition. Just give the zucchini a good rinse before you grate it.
Made this tonight, it is awesome, love It! Will keep this recipe for future use.
– Karen
More Veggie Sides and Casseroles
Did you make this recipe?
If you enjoyed this recipe, please leave a comment with a 5-star review at the bottom of the post. Thank you!
Watch How to Make It
Garlic Parmesan Zucchini Casserole
Ingredients
- 4 cups grated zucchini (about 3 ½ medium zucchinis)
- ½ teaspoon kosher salt
- ¼ cup finely grated onion
- 1 tablespoon minced garlic (about 3 cloves)
- 2 large eggs
- ½ cup grated Parmesan cheese, plus an additional 2 tablespoons
- 1 cup shredded mozzarella cheese
- ½ cup shredded cheddar cheese
- ½ cup Panko breadcrumbs
- 1 tablespoon salted butter, melted
Instructions
- Preheat the oven to 375°F. Grease a 1 ½-quart baking dish and set aside.
- Salt and drain the zucchini. Place the grated zucchini in a colander, sprinkle with the salt, and let it sit for about 10 minutes. Squeeze out the moisture by wrapping the zucchini in a dish towel and wringing it out a few times. The drier the zucchini, the better the casserole.
- Mix the filling. In a large bowl, combine the drained zucchini, onion, garlic, eggs, ½ cup Parmesan, mozzarella, and cheddar. Gently press the mixture evenly into the prepared dish.
- Bake uncovered for 20 minutes.
- Make the topping. Meanwhile, in a small bowl, stir the melted butter into the panko breadcrumbs and 2 tablespoons of Parmesan until combined.
- Top and finish baking. Sprinkle the breadcrumbs over the casserole and return it to the oven for 5 to 10 more minutes, until the top is golden brown and crisp.
- Garnish with fresh herbs or a squeeze of lemon and let rest a few minutes before serving.
Notes
- Drying matters most. A salad spinner lined with paper towels works well, and salting the zucchini hours ahead to drain gives an even drier start.
- Grating: A handheld box grater works, or run the zucchini through a food processor. No need to peel.
- Cheese swaps: Use an equal amount of just mozzarella or just cheddar, or try Monterey Jack, Colby Jack, Pepper Jack, Gruyere, Swiss, or Gouda.
- Yellow squash: Swap in yellow summer squash for some or all of the zucchini. A little shredded carrot is a nice addition too.
- For more kick: Add black pepper, crushed red pepper, or a teaspoon of Italian seasoning to the filling.
- Topping twist: Toss the breadcrumbs with olive oil instead of butter for a different flavor.
- To double: Double everything and bake in a larger dish, adding a few minutes to the bake time.
Nutrition
Originally published in February, 2017, this post was updated in July, 2026.
Husband loved this, and it was easy to make. My zucchini was drained very well but if I were to change anything I’d add something to make texture less like mashed potatoes ( baby food)
It’s a texture thing for me, any ideas?
Hi, Tan! I’m not sure that I totally understand. Zucchini is always going to be soft when it’s cooked, unless you just parboil or quickly cook it on the stovetop in a skillet. If you don’t like that texture, there’s not a whole lot that you can change in this particular recipe. Did you grate it coarsely, rather than using the fine side of a box grater? The coarser the shred, the less “mushy” it will be. I don’t typically find that it has a texture like mashed potatoes. You can usually get that grated texture in the finished dish. I hope that helps, and I’m glad that your husband enjoyed it! 🙂
Instead of grating the Zucchini, you could just dice or slice it in big chunks and it will definitely be less mushy for you. It’ll leave some crunch. My dad has the same issues with zucchini lol…
I loved this receipe! My dog needed out in the middle of the night and I cleaned up the leftover casserole just standing at the counter eating it. Thanks for this receipe. It was great.
Linda
Oh, good! I’m so glad that it proved to be the perfect midnight snack, too. 🙂 Thanks, Linda!
Fantastic! Made this today to use up extra zucchini and fell in love with it. Added 1 c cooked rice and only did half the cheese for my taste. Variations of cheese and herbs make this my sort of recipe. I’m making it agin next week to go with Easter lunch. Great recipe!!!
Wonderful! I bet it was great with the added rice, Cindy. Thanks for your note!
Just out of the oven. Smells divine. Hoping it tastes as good.
Now, about your web site. I realize you’ve abandoned a legal career (kudos from a mostly retired environmental lawyer on that) and ads support the site; but the pop-ups constantly slowed and clogged the site, and interfered with my cooking. Plus, I like to play music while I cook, and the constant video pop-ups kept interrupting the Spotify stream. As good as the recipe was, I would hesitate to use the site again due to the aggravating traffic. There needs to be a limit on the volume of commercial stuff being thrown out. Even now it blankets this page, making it hard to concentrate (which of course is the whole idea). Rest assured I would never purchase anything from an intrusive web advertiser. I suspect many others hold the line in the same way.
Increased my rating to five stars after multiple compliments and requests for the recipe. (I did warn that the website makes it hard to navigate, such that it might make sense to copy the ingredients onto a piece of paper, or maybe copy and paste. Things are just too busy and unstable.). Many thanks! Oh, and I put slices of tomato on top (by request of spouse), and let them cook a bit with the topping at the end. Worked great!
Thank you, Dirk. I always appreciate the feedback!
Hi, since you use frozen onions, have you tried frozen minced garlic? I get it at Walmart. It’s fantastic. I never peal and mince garlic anymore. I just use the frozen. I don’t know if I’m allowed to tell you the brand.
Ruth Trygstad
Ruth
Hi, Ruth! I haven’t tried that, but I’ll definitely look for it. I’ve used the jars of pre-minced garlic from the produce section, but I haven’t noticed the frozen option. Thanks for the tip!
First time making recipe, squeezed zucchini twice.ade it like the recipe. Came out Delicious. I will make thos again.
Awesome! Thanks, Lisa-Marie!
Hi I’m Johnnie Mae, I tried this recipe for the first time. Wanted to try something different from the usual. Went directly by the recipe including the wringing the water out of the squash, didn’t have the 3 cheeses but used what I had,boy did it turn out delicious, thanks for posting your recipe. Will try to show a picture Lisa Marie
Thank you, Johnnie Mae! I’m so glad that you enjoyed it!
A absolutely delicious!!! Plan on making it again this week!
Thank you, Linda!
Can I make this ahead of time without baking and bake at a later date (2 days)?
Hi, Kasey! Yes, I think that will work fine. Just make sure that you squeeze as much liquid out of the zucchini as possible before assembling. 🙂
I had some extra shredded zucchini so I thought I’d try this. Ohhh my, I wish I had alot more for a bigger dish cause this was absolutely delicious! Will definitely make it again soon!
So glad that it was a hit, Tina. Thank you!
This casserole is excellent…my favorite zucchini recipe!!
Thanks, Dolores!
I may try this with spiralized zucchini.
Sounds great! Let us know if it works well!
We have so many zucchini hardly knew what to do with them all. Well this recipe is delicious…it was a great side to go with freshly caught fish and corn on the cob . We love summer.
Thank you, Deborah! We love summer and all the fresh food available as well.
I cut back on garlic and quartered the zucchini. My boyfriend suggested putting cooked sausage down first so I did. Turned out great!
We’re so glad, Sonja! Thanks for sharing.
My husband and I loved this! When I make it again, I will use a shallower and wider dish to have a higher ratio of crunch to zucchini, but the flavor was awesome!
This is an easy and delicious recipe! I have a great tip for drying out the zucchini… a potato ricer, perfect!!
So smart! We’re glad you enjoyed the recipe!
Delicious & so easy to make! I doubled everything in the topping & used Italian flavored panko.
Thanks, Chris. I’m so glad that you enjoyed it!
Can this be baked in a baked pie shell instead of a dish?
We haven’t tested it but don’t see why not! Just keep a close eye on it so the crust doesn’t burn.
Hi! Currently waiting for this to come out of my oven and it smells delicious! I was wondering if you could prepare it and freeze it? Then let it thaw and bake, then add the topping, etc. I have a ton of zucchini to use up!
Hi Tatiana,
You can freeze the leftovers, but we don’t recommend doing so if you can avoid it as the texture is often altered once thawed.
This recipe is a family staple every Thanksgiving. I use tromboncini zucchini, onions and garlic from my garden and my family loves it. As a matter of fact, last year I didn’t make it and my guests asked where it was! So Happy Thanksgiving everyone and enjoy your time with family and friends. Buon appetito!
That makes me so happy to hear, Paola! Happy Thanksgiving to you!
We couldn’t stop eating it… so good. I didn’t have any cheddar on hand so just did 1/2 parm and 1/2 mozzarella. Added the zest of 1/2 a lemon. Broiled the crust for a few minutes in the end and the combination of crispy panko and cheesy zucchini kept us going back for more.
Thank you, Gregory. I’m so glad that it was a hit!