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.
My hubby and the boys enjoyed this casserole. Lots of compliments. Definitely need to spend more time draining the zucchini so it won’t be squishy. Still delicious. I used the leftovers in a lunchtime wrap today.
Thanks, Maria!
Thanks, Maria! So glad that you both enjoyed it!
Thanks for sharing
Very Amazing thanks so much for Sharing.
I just made this and it is absolutely delicious! Will make again for sure!
This looks like a wonderful recipe! I’m wondering if anyone has made it with a huge overgrown zucchini? My CSA keeps delivering me huge overgrown zucchini and I don’t know if any recipe will be good with zucchini this large.
Hi, Louise! I think you could definitely use an overgrown zucchini in this recipe. Just remove the really large seeds and you should be good to go!
I use large zucchini in recipes calling for eggplant since I have problems with eggplant. I love it in Moussaka.
That’s a great idea!
I wish it would cool down enough here in Texas to start making these recipes, but rest assured they are printed out and are being kept safely in my Home Management Notebook, ready for that first cold snap!Vodka Cupuacu
Hopefully soon, Lisa! I know how you must feel. This is our first week of cooler days and I’m loving it…
🙂
Love this recipe it was so simple!! I used my stand mixer and the recipe worked great I made this recipe for my daughters headstart class.Oreo Mcflurry recipe
Thank you!
I came across this recipe about a month ago and excited to make it for the second time. The flavors are outstanding and if you dry the zucchini properly, you will enjoy the perfect texture between the zucchini and panko breadcrumbs. Thank you for sharing such a delicious, easy recipe!
Thanks, Amber!
Love this recipe it was so simple!! I used my stand mixer and the recipe worked great I made this recipe for my daughters headstart class.Keto Meal Prep
Probably my ever best dish, I have made it now for forty years non stop….I don ‘ t put eggs, so it is lighter ….I usually slice the courgettes very thin in the magimix…then steam them…..I always make a big amount so I can freeze it after baking…in the baking dish…and reheat it in a hot oven…love it when the rice gets crispy at the bottom…..I also add leftovers green like kale….my mum add cooked tomatoes in the mix…she likes it moist….
Cheers
Christiane
Sounds perfect, Christiane!
An easy and truly delicious recipe. I love zucchini and was glad to have a new way to prepare it. This is a perfect dish to bring to gatherings – I can’t wait! I know it will be a hit! I served it with grilled chicken sausage in a little marinara sauce and they went together wonderfully. Thank you for the great recipe!
Thank you, Christine! I’m so glad that you liked it and that you’ll share it with friends and family, too. 🙂
I made this tonight with a couple of minor changes. I did not have cheddar, so I substituted smoked gruyere, which added a cheesy, smoky note to the mix. I also dusted the top with (hot) smoked Spanish paprika, which added a hint of spiciness but without being overpowering.
Finally, because i hadn’t read the directions all the way through before putting the casserole dish in the oven, i topped it with the crumb mixture before putting it in to bake for the first time. I was worried the top would burn after 35 minutes, but it was perfect.
I will definitely make this again, playing around with the cheeses and spices. It’s very versatile.
Your version sounds delicious, Valentina! Thanks for your notes, and so glad that you enjoyed it!
Wow! This is fabulous! My husband loved it as well. I used 2 zucchini and 2 yellow squash and the colors were beautiful
Thank you, Cary!
Hi, Patricia! You can certainly saute them first next time, but I haven’t ever found them to be crunchy in this dish. Maybe if you chop them a bit finer it would help? Or even grate them? Sorry it wasn’t a hit!
I made this for the first time today. It’s definitely a keeper since my garden produces SO much zucchini! I made it exactly as the recipe and the family loved it. Squeezing the grated zucchini in a towel was genius. All the moisture was gone so the casserole came out perfect and not watery. I also appreciate the size of the casserole. It’s perfect for us empty nester- so many other recipes make a huge 13 x 9 dish and that’s too much for us. Thank you for a delicious recipe!
Awesome! Thanks, Karen! I hope that you enjoy it with your fresh zucchini all summer long. 🙂
Yes, you squeeze out the water when you salt the zucchini, but you are also squeezing out all of the water-soluble vitamins, such as Vitamin C and all the B vitamins.
I don’t know why you eat, but I eat for nutrition.
What I do to keep the casserole from getting soggy while saving the vitamins is to put a layer of uncooked pasta in the bottom of the dish and then add the zucchini and the rest of the ingredients.
This is so delicious and easy to make. Will make this over and over!
Thank you, Dorene!
I didn’t excessively wring the zucchini and I felt the dish had a good balance of moisture. I used the larger-sized grater and I liked the bit of snap that the zucchini retained. I like the pasta idea. So did you use smaller pasta such as bows or elbow pasta? And just a single layer? Also, I did cook the dish longer, but I think my oven runs cool. And I used the Italian Panko crumbs.
Seriously Susan. You don’t have to be so uppity . Maybe try to phrase suggestions on the positive side next time. I made it exactly as written and it went fabulously with our Christmas ham dinner. Thank you Blair for sharing.
I’m so glad to hear that, Elaine! Thanks for your kind note, and merry Christmas!
CN you use frozen shredded zucchini?
Hi, Tara! I’ve never tried that, but I think it would work as long as you really strain the liquid from the thawed zucchini first. Let me know if you give it a shot!
I sauté mine and it comes out amazing
I was wondering what the heck to do with all the remaining zucchini I hand shredded while assisting the wife make her self professed Worlds Greatest Zucchini Bread. All kidding aside – it is very good bread.
I followed your recipe as best I could with the ingredients I had on had, all the while substituting where I saw fit AKA: “just winging it”. I used badia seasoning for the salt. I sprayed my 9×13 Pyrex with Pam and sprinkled it with salt, pepper and garlic powder prior to adding the mix. I used Amish candy onion, all cheddar cheese, and sprinkle Parmesan/Romano. I added about 1/4 finely chopped green pepper, a jar of drained and mushrooms and about a cup of chopped seasoned chicken breast.
Yum Yum! I’ll be keeping this recipe in my arsenal. Once the wife tastes it, I am sure she will claim the recipe as her own and expect accolades from All when she makes it! Ha ha
Hah! I’m glad that you found a good way to use up the rest of the zucchini, Dennis! Now I’m curious about your wife’s bread! 🙂
This is our new all time favorite zucchini recipe. Only thing I did different was using Italian bread crumbs instead of panko. I did not have panko in the house. It tasted awesome!
Thank you, Brenda! That makes me so happy to hear. 🙂
Can you make ahead?
Hi, Susan! Yes, I think you could prep it in advance and keep it refrigerated for a day or so before baking. The leftovers keep well in the fridge, too.