Summer side dishes don't get better than this zucchini casserole recipe! A crispy, nutty panko topping covers a saucy layer of pesto and zucchini.
If you have a mountain of zucchini or yellow squash in your fridge, this zucchini casserole recipe is just the thing for you! In fact, you should try this recipe even if you don’t have any summer squash on hand. The crispy, nutty Parmesan and panko topping contrasts perfectly with the saucy zucchini, pesto, and marinara underneath. It’s super simple to put together, and it can pass as a side dish or a meal on its own. Make this zucchini casserole recipe once, and you’ll have it on repeat all summer long.
Zucchini Casserole Recipe Ingredients
Here’s what you’ll need to make this delicious zucchini casserole recipe:
- Fresh zucchini, of course! I actually like to use a mix of yellow squash and zucchini in this recipe, but just one or the other would work fine too.
- Yellow onion – It gives the veggies a savory depth of flavor.
- Basil pesto – I toss it with the zucchini and onion for richness and fresh, nutty flavor.
- Marinara sauce – Tomatoes+basil are a match made in heaven, so I couldn’t resist adding tomato sauce to this dish! It helps make the middle of the casserole saucy and bubbly as it bakes.
- Panko bread crumbs and Parmesan cheese – Together, they create a crispy, savory topping for the saucy squash and onions. I like to turn the broiler on for the last few minutes of baking to get them brown and crisp!
Toss the zucchini slices and onions with the pesto, and cover the bottom of a casserole dish with the tomato sauce. Pile in the veggies, and smooth them into an even layer. Sprinkle the panko bread crumbs and Parmesan cheese on top, and add a pinch of red pepper flakes and a drizzle of olive oil. Bake at 375 for about 25 minutes, until the topping is golden brown and the squash is tender. Enjoy!
Find the complete recipe with measurements below.
Squash Casserole Recipe Tips
- Slice the zucchini as evenly as possible. The more evenly you slice the zucchini, the more evenly it will bake. You don’t want thin slices to become mushy before thicker ones cook through! I recommend using a mandoline to make sure that your slices are all the same width.
- Pat the zucchini dry. Zucchini can release a lot of water as it cooks! In order to keep your zucchini casserole from becoming watery, pat the zucchini dry before you toss it with the pesto. Better yet, set the sliced zucchini on a kitchen towel to drain while you prep the other ingredients.
- Smaller squash = better squash. This cheesy zucchini casserole comes out best when it’s made with small, firm summer squash. Large zucchini have a tendency to be seedy and watery, so I don’t recommend using them here.
- Make it vegan. This zucchini casserole is a great recipe to make vegan. Replace the traditional pesto with vegan pesto, and use my vegan Parmesan in the topping. Trust me, you won’t miss the cheese one bit!
Zucchini Casserole Serving Suggestions
This zucchini and squash casserole is a perfect side dish for 3-4 people. Serve it with your favorite protein, homemade pizza, or a simple pasta dish. I especially love it with these summer pasta recipes:
- Easy Pesto Pasta
- Spaghetti Aglio e Olio
- Linguine with Lemon and Tomatoes
- Garlic Herb Mushroom Pasta
- Fettuccine Alfredo
- Homemade Mac and Cheese
For more pasta recipes, check out this post!
Alternatively, make this zucchini casserole a meal on its own. Pile it on a bed of creamy polenta, cooked quinoa, or couscous, and add a handful of roasted chickpeas for a delicious, healthy dinner.
More Favorite Zucchini Recipes
If you love this zucchini casserole, try one of these zucchini recipes next:
- Perfect Grilled Zucchini
- Zucchini Lasagna
- Creamy Pasta Pomodoro
- Zucchini Noodles
- Stuffed Zucchini Boats
- Chocolate Zucchini Bread
- Or any of these 35 Best Zucchini Recipes!
Crispy Zucchini Casserole
- 4 cups mixed zucchini and yellow squash, thinly sliced
- ½ cup thinly sliced yellow onion
- ½ cup basil pesto
- ½ cup marinara sauce
- ⅓ cup panko bread crumbs
- ¼ cup grated Parmesan cheese
- Pinch of red pepper flakes
- Extra virgin olive oil, for brushing and drizzling
- Preheat oven to 375°F and brush the bottom of a 9x12-baking dish with olive oil.
- Set the sliced squash on a kitchen towel to drain some of the excess moisture while you prep everything else.
- In a large bowl, toss the zucchini and onions with the pesto.
- Layer the baking dish with the marinara sauce, followed by the zucchini mixture. Spread the zucchini into one even layer.
- Sprinkle the top with the panko, Parmesan, a drizzle of olive oil, and pinches of red pepper flakes. Bake until the zucchini is tender (but not mushy) and the top is crispy and lightly browned - about 25 minutes. I like to turn my broiler on for the last few minutes to help the topping become browned and crisp.
- Remove from oven and let it cool 20 minutes before slicing.
Hi! Made this recipe and everyone loved it! Wondering if it can be frozen after cooked or after prepped?
Hi Margaret, I’m so glad it was a hit! I think the zucchini might get watery after being frozen.
Yum! I salted the zucchini first, and let it sit in a colander to drain for about 15 minutes. Then I rinsed it thoroughly and dried it. I used bread crumbs because I didn’t have panko. And I served it with an egg on top with a runny yolks to break over the dish. So good!
Simple and delicious!
Another big zucchini fan here, and I just made this wonderful dish. I love it! I had already made a batch of basil/celery leaf pesto (using the big dark-green leaves of the celery – a delicious addition to the pesto), so it was perfect for what I had on hand. Only change I made was to add a good bit more onion, because I love onions. Will be making this all the time from now on in. Thanks for this recipe!
In previous comment I forgot to mention I made the pesto using a combination of spinach and arugula and walnuts, along with the vegan parmesan. It’s a delicious alternative to the regular basil pesto. I’m not much of a fan of basil and try to use other greens in place of.
Loved this squash recipe! Used a combination of crookneck and zucchini from our garden and used Vegan parmesan to make it vegan. It is delicious and a great way to use up some of the (very prolific) squash. Always looking for new ways to prepare the abundant zucchini and crookneck.
This recipe is fantastic! I made this a couple weeks ago, exactly as written and everyone loved it so I just finished making this up for dinner tonight (a little early, but I have a 4pm meeting). I added in slices of tomato fresh from the garden and it looks so colorful! I also used the recipe for homemade marinara this time around, but made it with my own fresh tomatoes instead of canned. I know the tomato slices will cook more quickly than the rest of the dish, but we love tomatoes in just about any format, and since I have too many coming out of the garden daily, most of my recipes this time of year have tomatoes tossed into them in some way, shape or form.
Hi Elisa, I’m so glad you loved it!
I just made this using stuff from the farmers market, and instead of making the pesto from scratch, I made the tomato sauce from scratch 🙂 It was really good!
My son who is new to cooking made this today. It was pretty good. while we were cleaning up I noticed a pile of sliced onions on the counter! He took your suggestions to set the onions aside very seriously and did not add them to the zukes when he stirred in the pesto. I’m pretty sure that the onions would have been a great addition, you might want to edit the instructions for new and very literal cooks 😉
Hi Shelley, just fixed it – thank you for pointing that out!
My husband would do exactly the same thing! 😅
I just love zucchini. I just always wanted to try something new. (till now i’m just making zucchini pancakes, bake them in the pan with batter and sprinkle with garlic anr parsley and sometimes make omelet with them) thank you for this recipe. This was reaaaaally tasty! will try something else!
so glad you liked this one too!!
Just tried it tonight, it was delicious! I never though zucchini could taste that good!
Merci!
Just threw this is the oven! Just some notes on the recipe – you never mention to toss the squash in with the pesto, it’s just referred to as “pesto-ed squash”, which was confusing. Also, you didn’t say what to do with the onions, which I didn’t realize until I’d already put the panko layer on top. I tried to squeeze them in under some of the zucchini, but had to leave out most of them. I’m excited to have it tonight, just thought I’d pass along a few critiques!
I made this last night & it did not disappoint! Even my boyfriend, who has a very pronounced distaste for zucchini & squash, went back for seconds. We were both blown away by the delicious layers of flavor & how healthy of a dish it is. I made it vegan & added cashews to the pesto instead of pine nuts then combined nutritional yeast with the breadcrumbs on top. We made half of the dish with breadcrumbs & half without – both were completely delectable.
Thanks for a recipe that tastes as good as it looks! This would be a perfect potluck dish & I wish summer wasn’t almost over so I could keep making it!
I’m so glad you liked it – thanks for coming back to let me know! I’ll have to try it with nutritional yeast & breadcrumbs next time 🙂
What a great idea looks tasty 🙂
Thank you so much for the recipe! But since it contains zucchini, my advice is to buy only veggies that are shorter than 8 inches because the longer ones can be bitter 🙁 A while ago I’ve noticed that some zucchinis are just more bitter than other and then I’ve found this explanation:
http://www.listonic.com/protips/get/soeextwjle
This looks incredible! Wow – such a great dish!
This looks so delicious! I must make it before our zucchini’s disappear for the season!