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!
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
- 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.