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.
Is this easy to make before (maybe the morning of?) and then cook later on for dinner?
Hi, Kristin! Yes, you can definitely make it ahead of time. Your best bet would be to bake it through Step 4 in advance. Then freeze or refrigerate the baked zucchini until you’re ready to finish it. Then you just need to top it with the breadcrumbs and finish baking when you’re ready to serve. Hope that helps! 🙂
I am allergic to eggs. What is a good alternative for me to use in this recipe??
Hi, Alicia! I’m honestly not sure. I haven’t tested this recipe without the eggs, and the eggs are important for holding the casserole together. If you omit the eggs, you would want to find something else to act as a binder. I know that there are some commercially made egg replacers, which are often made with potato starch, tapioca starch and leavening. These are used in baking, but can probably be used here, too. Another option that some folks use in baking is to replace eggs with “flax eggs.” Again, I haven’t actually tried this, but you could see how it goes if you’re curious. To replace one egg, whisk together 1 tablespoon (7 grams) of ground chia or flaxseeds with 3 tablespoons (45 grams) of water until fully absorbed and thickened.
Hope that helps!
Thanks you I may someday have to experiment with that egg substitute. Can you taste the egg in the dish, or is it just binding like as it is in a cake, where as the cake does not taste like egg.
Hi, Alicia! The flavor of the egg doesn’t stand out much in this dish. It’s more of a binder in this case. 🙂
I made this dish and absolutely loved it. However, I did not shred the zucchini… I cubed it. Even though I used salt, I did not get water from it. By keeping it in the oven 10 more minutes before the breadcrumbs it cooked thoroughly and it was not watery. ( the water helped cook the cubes). Then I put the breadcrumbs on and back in the oven. It was delicious!
That’s a great tip, Meredith! Glad that you enjoyed it!
I have heard that the liquid from canned garbanzo beans can be substituted for eggs.
I love zucchini but some of my family members not so much……they loved this recipe!!!!!!
Oh, good! I’m so glad to hear that, Cris. Thanks for coming back here to let me know. 🙂
You’re the one who is allergic. Don’t you have this figured out by now? I have food, allergies, but I don’t expect recipe inventors to accommodate them all. I expect myself to have some knowledge, and if I don’t, I’m going to some research. I don’t get why everybody thinks that every recipe inventor should cater to their every single individual quirk.
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
Sounds perfect! Thanks, Sheba!
This casserole is fabulous. I made a smaller version because I didn’t have enough zucchini but will now be making full recipes often!
Thank you, Kelly! 🙂
I really enjoyed this zucchini casserole. 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.
Yumyumyumyum!
Thanks for your note, and I’m so glad that you enjoyed it! The zucchini is very mild, isn’t it? I think that’s why my kids and husband love it so much. 🙂
I just want to say how delicious this dish was. I made it while visiting my daughter because she loves squash. It was a huge hit. This pin on my board is pinned repeatedly everyday. There must be lots of zucchini lovers out there!!! Thanks so much for your creativity!!!
Hi, Laurie! Thanks so much for your kind note and for letting me know. A good zucchini recipe is always helpful to have on hand — especially in the summer. So happy that your family enjoyed it!
What can I replace the eggs with? May daughter is allergic to eggs.
Thanks,
Kimberly
Hi, Kimberly! I’ve never made this dish without eggs, so I’m not sure how it will work with different ingredients. That said, I do know that vegans and other folks with egg allergies often substitute regular eggs with “flax eggs.” Have you used flax eggs before? To make a flax egg, just mix one tablespoon ground flaxseed meal with three tablespoons of water. Mix together, and let sit in your fridge for 15 minutes to set up and thicken. That’s equivalent to one egg, so just double or triple depending on how many regular eggs you’re replacing.
Thanks! I never heard of that before. I will have to buy some – thanks!!
You’re welcome! 🙂
okay so I made it last night…overall I liked it. I tried the “flax egg ” mixture instead of the egg like you suggested. Since I’ve never made this dish before I’m not sure what the consistency should be like, but I think mine was more on the wet side. I’m not sure if the zucchini wasn’t drained enough or if it was the “flax egg”.
I also think I put too much garlic in…I think 1 tablespoon might be too much.
My daughter (who is allergic to eggs) liked it in the beginning then said she didn’t like it. But she almost finished her small bowl of it. Again, I think it was the overpowering garlic taste.
Either way I would make it again with less garlic and have her try it again!
Hi, Kimberly! I’m glad to know that it worked out overall. When it comes to draining the zucchini, I like to wrap it in a dish towel and literally wring it dry — squeezing it as hard as I can until no more water is coming out. You would be amazed by how much moisture is released, and I think that you’ll find the casserole is not watery at all if you do it this way. Hope that helps, and thanks for sharing your feedback! 🙂
I have done it with out eggs and it’s delicious
Awesome! Thanks, Carrie!
Made this tonight, it is awesome, love It! Will keep this recipe for future use.
Perfect! Thanks, Karen — I’m so glad that you enjoyed it! 🙂
I made this for supper last night and it is amazing!! A hit with the whole family! This is a keeper recipe! Thank you!!!!
I’m so glad to hear that the family enjoyed it, Cheryl! Thanks for letting me know!
I’ve been looking for a new dish to take to Thanksgiving dinner. This sounds like a yummy, updated version of a classic family dish!
Wonderful! Enjoy, Jen! It’s one of our favorites! 🙂
Made this tonight for the first time and I really liked it. I grated 2 cloves of garlic and did find the flavor on the strong side but I like garlic, so I was ok with it. I also know grating garlic releases a stronger flavor so that might be part of it. Great recipe!!!
Thanks, Heidieh! 🙂
If planning to double the recipe, would you also double the time in oven? Very excited to try!
Hi, Kristelle! No, I wouldn’t double the time in the oven. You might need to add a little bit of time to accommodate the larger dish, but probably not much. I would bake it uncovered for 25-30 minutes before adding the buttered breadcrumbs on top. Then return to the oven for the final 5-10 minutes. If that still doesn’t seem long to heat it through, you can cover the top lightly with foil (to prevent the top from getting too brown) and leave it in the oven for a few more minutes, as necessary. 🙂
plan on making this in a 9×13 dish for Easter Sunday…..I was going to almost double amounts ….cooking time suggestions?
Hi, Bernie! Doubling the ingredients for a 9 x 13 dish should work perfectly. The cooking instructions should remain largely the same; although you might want to add about 5-10 minutes to the overall cooking time to make sure that it’s properly heated through. Just check it after the first 20 minutes and see if the zucchini mixture looks adequately warmed through. If not, pop it back in the oven for 5 more minutes before adding breadcrumbs to the top. Hope you love it!
I made this last night for 8 guys who were working on my house. I doubled the recipe and you would have thought that it was the best thing these guys have ever eaten. It was all devoured by the end of the meal! Definitely going to make this again!
Wonderful! It’s a huge WIN when a veggie dish gets the stamp of approval from a group of guys! 🙂
This recipe was wonderful, I followed the recipe exactly minus the onions and when you follow directions its comes out exactly the way it should be , no ruuny mess over here lol.
Perfect! So glad that it worked, Robin! 🙂 Thanks for your note!
I made this tonight and it was so good! My husband even commented on how great it tasted especially with so much zucchini in it. Will be making this again, as our family of 3 devoured pretty much the whole thing in one sitting. Thanks for the delicious recipe!
Wonderful! Love when the husbands approve of veggie dishes! 🙂
Can you shred the zucchini instead of grating it? It seems like it would take a very long time to grate the zucchini.
Yes, I think that would probably work fine.
Thank you, Blair!
How did shredding vs grating work out? Glad you asked as when I read grated, I assumed shredded. Agree grating would take forever!
Also wanted to make ahead but wondering if 10 minutes after adding pinko would reheat it up sufficiently.
Hey, Karen! I would think that it will likely need about 15-20 minutes to reheat completely, so maybe sprinkle on the topping towards the end.
Do you measure the zucchini before or after you squeeze it out? Kind of confused. Sounds good tho.
Measure it before squeezing it out. 🙂
I made this last night to go with grilled lamb loin chops.
I added a cup of cooked white rice to the mixture and used lowfat cheeses.
It was excellent!!! My husband ate two helpings. I will definitely make this again.
Oh, great idea to add the rice! Thanks, Nancy!
I have made this recipe 3 times already! Great stuff!
1st time) Made as recipe states and it was a hit, even with those who thought they didn’t like zucchini.
2nd time) Tried being creative and tried squeezing the zucchini with a potato ricer – turns out it does NOT work as good as an old fashioned tea towel. Lesson learned.
3rd time) Went back to the original way! Having some health issues, so I reduced the cheese and added some already cooked quinoa. Eating it now and it’s fabulous. Thanks so much!
Thanks, Leela! I’m so glad that you love it, too. I just made it last week and I enjoyed some leftovers for lunch the next day. It’s so good that I could eat it like an entree! Love the idea of adding quinoa to make it more filling!
I have cups and cups of frozen zucchini from my garden last year. I’m trying to use it up and found your recipe. Do you think this recipe will work if I use frozen zucchini?
Hi, Monique! I think it would probably work fine, but I would definitely thaw the zucchini first and really make sure to squeeze out any excess liquid. 🙂
Thinking about adding precooked ground turkey to the dish for an all in one. Thoughts? TIA
That sounds like a delicious idea! I bet it will work really well. Let me know if you give it a try, Adair!
Oh my dammmmit! Deeeelicious! !
Hah! Thank you! 🙂
Made this using yellow squash and it was delicious. Topped it off with Frenchs onions and Frenchs Jalapeno. Gave it a nice kick. Will make again!!!
YUM! So glad that you enjoyed it, Renee!