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.
I’ve made this three times. The last time I used yellow squash and carrots because it was what I had. Just as yummy as the first 2 times. My husband requests it.
Awesome! Thanks, Cerina!
Do you peel the zucchini?
Hi, Jana! No, you don’t need to peel the zucchini. 🙂
I had a recipe for zucchini that was similar. I bakedit and cut it into squares for appetizers. It was delicious, but I can’t find
the recipe. Could this be modified to do the same thing?
Hi, Sherrie! This might work, but I don’t think that it will cut as neatly into squares as you might hope. These two recipes sound more like what you’re looking for, so take a look and see if they’re similar to your old recipe:
Zucchini Pie: https://www.theseasonedmom.com/zucchini-pie/ (just bake it in a square pan and slice into squares instead of using a round dish)
or
Cheesy Spinach Squares: https://www.theseasonedmom.com/aunt-bees-spinach-cheese-squares/ (use zucchini instead of the spinach, perhaps?)
Hope that helps!
Recipe is listed as a Weight Watcher but what are the points per serving?
Hi, Carolyn! I haven’t listed the recipe as “Weight Watcher friendly,” so I’m not sure where you saw that. I’m not familiar with exactly how to calculate points for Weight Watchers, so I’m not any help in that regard. Maybe you can use the nutrition panel provided below the recipe to help you calculate the points? Again, sorry that I’m not able to be more helpful! I hope that you get to try it, though — we love this dish! 🙂
Great and simple recipe. I added a can of fire-roasted diced tomato (simply because I love zucchini and tomato together) It was wonderful.
Sounds delicious! Thanks, Amanda!
sy and turned out great. I used thawed roasted garlic I had in the freezer, doubled the recipe and used as a main dish. It came out pretty too – so I’ll have another option for potlucks! Thanks for the tip to wring out the zucchini – that’s always been a problem for me and zucchini!
Yay! I’m so glad to know that you’ve found a keeper, Johanna! Thank you for taking the time to leave a comment!
I cut the recipe in half since it was just for myself and added a cup of mixed vegetables. Love it! Used stuffing mix instead of Panko breadcrumbs. Delicious!
Sounds perfect, Ashli! Thank you!
Thankyou for this recipe! I made it as written except I added a kittle leftover Feta cheese that I had in the fridge.
Excellent dish!
Definitely will make this again, yum.
I bet the feta was delicious! Thanks so much for taking the time to leave a note. 🙂
I just made this for dinner tonight and it wasn’t a huge hit. I think the onion & garlic combo overpower the other flavors- and I think the cheese might be too much. I usually love zucchini but this wasn’t great
I made it with a few changes because of health reasons. First change was I sliced the Zucchini instead of grating it. Second I deleted the salt and 3rd I deleted both the mozzarella and the cheddar cheeses. Even though I made these changes it turned out FANTASTIC!
I did make it the second time Exactly as per the instructions. I didn’t like it. It was OK, but after tasting the first one, that’s all it was.
Now I friends making your Recipe (my way) with other vegetables and the love it. Thank you very much. This is one of the best things I make and can eat, happily.
That’s great to hear, Bonnie! Thanks for sharing your changes and for taking the time to leave a note. 🙂
Thank you for responding.
Question:.Do you have any other Recipes that can be adapted to fit with Chronic kidney disease all stages?
Hi, Bonnie! I’m not familiar with the dietary restrictions associated with chronic kidney disease. If you can give me a few more details about what you’re looking for, I might be able to direct you to some other recipes. 🙂
Thank you for responding.
Question:.Do you have any other Recipes that can be adapted to fit with Chronic kidney disease all stages?
Taste was great. Personally, I would grill the onions and garlic before adding to the recipe.
We enjoyed this casserole tonight with our dinner. I substituted white cheddar cheese for regular. This turned out perfectly cooked in our toaster convection oven. : )
That’s wonderful, Nancy! Thanks for taking the time to come back here and let me know!
I was torn on how to rate this recipe. It is fantastic, but for me it’s not a casserole. It’s definitely an egg bake. Leaving off the crackers made a delicious keto egg breakfast. If you like garlic and eggs, this one is a winner, but it’s not a casserole.
I made this several times last summer and it was always a hit. While reviewing the recipe before this year’s first zucchini I thought I would drop a few comments. I usually use an extra egg because I like the casserole a little firmer. Also if I use about half the onion out of dried, chopped onions it takes on part of the zucchini moisture and makes draining/squeezing a little less critical. I’m with the folks who add hot sauce, though a small (cooks preference on amount) of chopped fresh peppers is an interesting flavor. Other additions I’ve found work for me: fresh basil, ham or chicken, top with feta crumbles instead of bread crumbs for gluten free. Thanks for the great recipe.
Thanks for those helpful notes, Jim! Your additions sound perfect!
WE just made this recipe at a Hosiptal kitchen, and its sooo good! we will be serving it to the whole hospital tomorrow!
That’s amazing, Sophia! Thanks for your note. I hope that the hospital patients enjoy the dish. 🙂
I made this yesterday. It came out perfect. I used zucchini from our garden. Thank-you. Very gtood
I made this yesterday. It came out perfect. I used zucchini from our garden. Thank-you. Very good.
Thanks, Donna! I’m so glad that you enjoyed it! Can’t beat garden-fresh zucchini. 🙂
I made this tonight with a slight change. Instead of using the mozzarella and cheddar cheeses, I used ricotta and the Parmesan. My husband is not a huge fan of cheeses so this was what we agreed on. I also used yellow squash and the zucchini. OH MY GOODNESS, so so good. I think next time I’m going to saute the onions first. They still have a slight raw taste to me (which in all fairness could be my oven). Other than that, I wouldn’t change a thing. Hubs said it’s definitely a keeper!!! Thank you so much for sharing your recipe!!!
I’m so glad that you both enjoyed the dish! Thanks for sharing your twist. 🙂
We loved this recipe. For getting rid of the excess moisture from the zucchini, I put it in my salad spinner and “spun” the excess moisture out after 10 minutes. It worked well.
I also cut back just a little bit on each of the cheeses to help reduce the fat content. It was still delicious. The panko bread crumbs on the top really puts it over the top. My hubby is not a fan of zucchini but he liked this so well, he suggested I make it at Thanksgiving. Who knew???
Thanks!
Yay! So glad that your husband even approved! 🙂
We loved the recipe. I used a salad spinner to get the excess moisture out of the zucchini after it sat for the 10 minutes. I also cut back just a little bit on each of the amounts of cheese mainly to help reduce the fat content of the dish. My husband who is not a fan of zucchini, really enjoyed it as well. He even suggested serving this dish at Thanksgiving this year. Who knew??
Thanks!