This zucchini casserole is an easy summer side dish ready in about 30 minutes. Fresh zucchini is sautéed with garlic and shallots, then finished briefly under the broiler with a crisp Parmesan breadcrumb topping. Parsley and thyme keep the flavors light and aromatic, without the heavy cream or layers of gooey cheese found in many squash casseroles. The result is tender-crisp zucchini that stays firm rather than turning soft or mushy.
When gardens and markets are overflowing with summer squash, this zucchini casserole is a fresh, flavorful way to enjoy it. I trim away the soft, seedy centers for a firmer texture, briefly sauté the zucchini with garlic and shallots, then spread it in a shallow baking dish to maximize the crisp topping and help the zucchini stay tender-crisp.
Zucchini Casserole Recipe Snapshot
- Summer side dish - Fresh, light, and perfect for peak-season zucchini.
- Ready in 30 minutes - Quick stovetop cooking with a brief broil to finish.
- Tender-crisp zucchini - Stays firm instead of turning soft or mushy.
- Crunchy Parmesan topping - A shallow dish creates more golden crust in every serving.
- Light and herby - Garlic, shallots, parsley, and thyme add plenty of flavor without cream or heavy layers of cheese.
Here's another easy summer casserole, my zucchini tomato casserole with herbs with south-of-France flair.
Ingredients You'll Need
- Olive oil - My go-to for sautéing the vegetables and crisping the breadcrumb topping. Avocado oil or another neutral, heat-safe oil also works.
- Zucchini - Green zucchini is classic, but a combination of green zucchini and yellow summer squash adds beautiful color.
- Shallot - A small member of the onion family with a delicate sweetness. Yellow onion works too.
- Garlic - Fresh garlic cloves provide the best flavor.
- Fresh herbs - Parsley and thyme add fresh, aromatic flavor to the casserole.
- Breadcrumbs - Use regular breadcrumbs for a fine, even crust, panko for a lighter crunch, or coarsely ground homemade breadcrumbs for a more rustic topping. Use gluten-free breadcrumbs if needed.
- Parmesan cheese - Adds salty, nutty flavor and helps create the crisp, golden topping.
Please see the recipe card for measurements, salt, and pepper.
Chef's Tip: Trim the Seedy Centers. Most zucchini have a pale, spongy center. Quarter the zucchini lengthwise and trim it away before chopping. Removing that soft center gives the casserole firmer, meatier pieces that hold their shape and are less likely to turn soft or watery.
Substitutions and Variations
- Thyme - If fresh thyme is unavailable, use 1 teaspoon dried thyme in place of 1 tablespoon fresh.
- Parmesan - Pecorino Romano or Piave are good substitutes and will give the topping a slightly sharper, saltier flavor.
Chef's Tip: Use a 1-quart shallow gratin or casserole dish rather than a deep baking dish. Spreading the zucchini into a thinner layer allows moisture to evaporate instead of getting trapped, helping the zucchini stay more tender-crisp while giving you more surface area for a golden, crunchy breadcrumb topping.
How to Make Zucchini Casserole
The zucchini is sautéed just until crisp-tender, then finished briefly under the broiler instead of baked for a long time. This keeps it from becoming soft, watery, or mushy while still giving the Parmesan breadcrumb topping time to turn golden and crisp.
- Quarter zucchini lengthwise and slice out the seedy centers with a sharp knife.
2. Next, slice the zucchini into about ½" size pieces on the diagonal.
3. Heat the oil over medium high in a 12" frying pan.
4. Add the zucchini to the pan and sauté, stirring occasionally, until the edges start to brown but the pieces are still crisp-tender, 5-6 minutes.
5. Remove the zucchini to a plate and hold near the stovetop.
6. Saute the shallot until soft, add garlic and cook another 30 seconds, add the herbs and stir. If pan is dry add a few drops of olive oil.
7. Add the zucchini back into the pan and turn to coat with the shallot mixture.
8. Pour into a 1 quart shallow baking dish.
9. Mix the breadcrumbs, parmesan cheese, and olive oil.
10. Spread the crumb mix evenly over the top of the zucchini. Pre-heat the broiler with the rack in the center of the oven or the second level down. Broil 1-2 minutes until golden, depending on the level. Watch carefully-it can go from golden to over-browned in less than a minute. Don't walk away.
Serving Suggestions
This zucchini casserole pairs well with almost any summer meal. Serve it alongside grilled chicken, grilled flank steak, smoked pork tenderloin, salmon, shrimp, or your favorite barbecue recipes. It also makes a delicious side for burgers, grilled sausages, or a simple rotisserie chicken.
For a lighter, vegetarian meal, pair it with cooked grains such as quinoa or farro, or enjoy it with crusty bread and a simple salad.
Recipe FAQs
Yes. This zucchini casserole uses no eggs or creamy binder. The zucchini is briefly sautéed with shallot, garlic, and herbs, then topped with Parmesan breadcrumbs and quickly broiled until golden and crisp. It is much lighter than the creamy-style recipes with eggs, cream, or a lot of cheese.
Yes, but for the best texture, prepare the zucchini and topping separately, then assemble and broil just before serving. This keeps the breadcrumb topping crisp and the zucchini from becoming too soft.
Absolutely. Yellow summer squash works well on its own or combined with zucchini for extra color. Cook it the same way, just until tender-crisp.
Not always, but I recommend it for medium to large zucchini. Trimming away the pale, spongy center helps the zucchini hold its shape and keeps the casserole from becoming watery or too soft.
More Summertime Side Dish Recipes
Looking for more super summer side dish recipes? Try these or take a look at this link for more summertime recipe ideas.
⭐️Did You Make This?
If you make this zucchini casserole, lpease drop me a comment an dlet me know who you enjoyed it. Your comments help other readers, and I love hearing from you.
📖 Recipe
Zucchini Casserole with Parmesan Crust
Equipment
- 1 quart shallow baking dish, broiler safe
Ingredients
- 2 tablespoons olive oil divided use
- 2 pounds zucchini about 4 medium, 8 ounces each
- 1 large shallot finely chopped
- 2 large garlic cloves finely chopped
- 2 tablespoons freshly chopped parsley
- 1 tablespoon freshly chopped thyme leaves or 1 teaspoon dried
- ⅓ cup grated Parmesan cheese or Pecorino Romano or Piave for the Parmesan cheese.
- ⅓ cup toasted breadcrumbs, gluten-free or wheat see notes below
- ¼ teaspoon sea salt
- ¼ teaspoon ground black pepper
Would you like to save this recipe?
Never lose a recipe! We'll email this post to you, so you can come back to it later.
Instructions
Set up the Broiler
- Position an oven rack in the middle of the oven. Preheat the broiler. Lightly oil a shallow 1-quart broiler-safe baking dish with olive oil or spray it with avocado oil.
Make the topping
- Combine the breadcrumbs, Parmesan cheese, and 1 tablespoon of olive oil in a small bowl. Stir until the crumbs are evenly coated and set aside.
Trim Zucchini
- Trim the ends from the zucchini, then cut each one into quarters lengthwise. Lay the quarters flat and, holding your knife parallel to the cutting board, trim away the seedy, spongy center. Cut the zucchini into bite-sized pieces.Removing the soft center helps the zucchini stay firmer and prevents the casserole from becoming soggy.
Cook Zucchini and Shallots
- Heat the remaining 1 tablespoon of olive oil in a large 12-inch sauté pan over medium-high heat. Add the zucchini and cook, stirring and turning frequently, until just beginning to soften and lightly brown around the edges, 5-6 minutes. Do not cook it until completely tender.Transfer the zucchini to a plate so it does not continue cooking while you prepare the shallot and garlic.
Cook the Shallot and garlic
- Reduce the heat to medium low. Add the shallot to the same pan and cook for 2-3 minutes, until softened. Add the garlic and cook for 30 seconds, stirring, until fragrant. If the pan is dry add a few extra drops of oil.Stir in the fresh thyme, parsley, salt, and black pepper. Return the zucchini to the pan and toss briefly to combine and coat it with the shallot, garlic, and herbs.
Broil the Casserole
- Transfer the zucchini mixture to the prepared baking dish and spread it into an even layer. Sprinkle the Parmesan breadcrumb mixture evenly over the top.Broil until the topping is golden brown and crisp. Watch closely, as breadcrumb toppings can brown quickly under the broiler, even in a minute or 2. Don't walk away from the broiler. Cool a bit and serve warm.
Notes
Nutrition
Would you like to save this recipe?
Never lose a recipe! We'll email this post to you, so you can come back to it later.
Kate S says
Easy and delicious!
Sally Cameron says
Thanks for commenting Kate! Glad you enjoyed it!
Lois says
Fabulous! Nothing more can describe it if you are zucchini lover and even if you are not!
Mrs. O says
The recipe says, “1 1/2 tablespoons olive oil divided use”. I only see the olive oil being used to fry the zucchini. Did I miss a step?
Sally Cameron says
Hi Mrs. O. You mix part of the olive oil with the topping, then use the rest to cook the zucchini. I checked the recipe and it's there in the description, but I did clarify it a bit. Hope that helps! Thanks for the question and hope you enjoy this. I think I'll make it tonight! I also foxed a photo, so thanks again.
Kristen says
Thank you for sharing this recipe - I made it over the weekend and it was fantastic! FYI - After dinner we had half the casserole left over, and with no room in the fridge I decided to experiment. I blended the remaining portion in a food processer and mixed with a little sour cream / greek yogurt.... let me tell ya it makes one HECK of an amazing dip. Like, reeeally good.
Sally says
Thanks for shring that tip Kristen! Sounds fantastic. I'd never have thought of turning leftovers into a dip! Glad it worked so well for you!Very creative!
Mary@SiftingFocus says
Sally, I'm always looking for new and delicious twists on preparing zucchini. Love the healthy and simple approach you took in this recipe.
Madonna/aka/Ms. Lemon says
Our family calls zucchini our new potato. This looks delish.