Italian Zucchini Casserole is the perfect way to use up all your summer zucchini! This delicious side dish combines thinly sliced zucchini, tomatoes, and onions that are layered with cheese, and herbs, topped with a garlicky breadcrumb mixture, and baked until bubbly.
This post may contain affiliate links. Our disclosure policy.
Zucchini is one of my favorite ingredients because it’s incredibly versatile and easy to grow.
I use it all the time, especially, in summer, and make this Italian zucchini casserole often.
It’s one I grew up eating, and one I hope my kids will make for my grandkids in the future.
The layers of tomato, zucchini, and onion with herbs, cheese, and breadcrumbs are just delicious and the perfect side to grilled chicken thighs or grilled pork chops.
While this zucchini onion tomato casserole is predominantly a summer dish, I make it all year and often for Thanksgiving!
Want To Save This Recipe?
Enter your email and we'll send it to you. Plus, get great new recipes from us every week!
Recipe Ingredients
All ingredients for this recipe are shown in the pic below and special notes are made in this bulleted list to assist you.
- Zucchini. I prefer to use medium zucchini for Italian zucchini casserole. Save the small zucchini for dishes like spaghetti alla Nerano.
- Tomatoes. Beefsteaks or heirlooms are great as are plum tomatoes. Truthfully, any type of tomato will work since the dish is roasted uncovered allowing the water from the tomatoes to evaporate.
- Oregano. I use dried Sicilian oregano (as pictured above) for zucchini casserole because it adds tremendous flavor. I recommend using the packaged dried flowers over the jarred version for best results.
See the recipe card for full information on ingredients and quantities.
How to make it
Each number corresponds to the numbered written steps below.
- Preheat the oven to 375f and set the rack to the middle level. Finely grate 1/2 cup of Pecorino Romano cheese dividing 1/4 for the breadcrumbs and 1/4 for the zucchini. Mince 2 cloves of garlic. Using a mandoline (with a safety attachment) or a sharp knife, slice 3 medium zucchini into thin slices, lengthwise. Thinly slice 2 large tomatoes and 2 large onions and set aside. Drain the sliced tomatoes and pat them and the zucchini slices dry with paper towels too remove excess liquid.
- In a bowl, mix together the garlic, 1/2 cup of breadcrumbs, 1/4 cup of the grated Pecorino Romano, 1/2 teaspoon of crushed red pepper flakes, 1 teaspoon of Sicilian oregano, and 3 tablespoons of extra virgin olive oil and set aside.
- Oil a 9×13 baking dish (below I used two smaller baking dishes) and place a few layers of zucchini, then drizzle with extra virgin olive oil and season with salt and pepper to taste. Add a pinch of Sicilian oregano and some of the Pecorino Romano cheese.
- Add a few layers of onion and season with the salt, pepper, Sicilian oregano, and Pecorino Romano in the same manner.
- Layer the tomatoes and drizzle with some extra virgin olive oil, and season in the same manner with the salt, pepper, Sicilian oregano, and cheese, then sprinkle the breadcrumbs on top and add a bit more grated cheese. Drizzle some more extra virgin olive oil until the breadcrumbs are well-moistened.
- Bake for 45 minutes or until bubbly. Much of the liquid should have evaporated at this point. If the breadcrumbs aren’t golden enough, you can broil them for 1-2 minutes but watch carefully to prevent burning. Allow the zucchini casserole to settle for at least 10-15 minutes before serving with your favorite main course. Enjoy!
Top tips
- Slicing. Whenever using a mandoline it’s important to follow the manufacturer’s instructions for safety. Always use the safety guard and take your time when using one. You can 100% use a knife for this recipe.
- Wetness. Drain the sliced tomatoes and pat them and the zucchini slices with paper towels to remove excess water. If the casserole is too wet after 45 minutes of baking you can carefully drain some of the liquid or pull it out with a bulb blaster or paper towels and bake for another 5-10 minutes before serving.
- Seasoning. This is one of those recipes where the seasoning doesn’t need to be so precise. Depending on how many levels of layers you have you may need to use more or less. Keep in mind that Pecorino Romano is on the saltier side so you many not need as much salt as you’d think.
- Let it settle. This Italian zucchini tomato casserole should be allowed to settle for at least 10-15 minutes before serving, but it can sit for longer and is also delicious at room temperature.
More zucchini recipes
If you’ve been blessed with an abundance of zucchini, here are a few of my favorite recipes to try.
- Stuffed zucchini boats – with sausage, marinara, and mozzarella.
- Zucchini bread – with a cinnamon swirl and the best cream cheese frosting.
- Italian zucchini soup – with plum tomatoes, herbs, and broken spaghetti.
- Zucchini pizza – Grandma-style pizza topped with razor-thin zucchini.
If you’ve enjoyed this Italian Zucchini Casserole Recipe or any recipe on this site, give it a 5-star rating and tell us about it in the comments below.
We strive to satisfy a number of learning styles. If you are someone who prefers to learn by watching, you can find most of our recipes on YouTube and our Facebook Page.
For more never-before-seen recipe videos, become a Patreon member today!
Italian Zucchini Casserole
Ingredients
- 2 large slicing tomatoes thinly sliced
- 3 medium zucchini thinly sliced lengthwise
- 2 large onions thinly sliced – yellow, white, or red are all fine
- salt and pepper to taste
- 2 teaspoons Sicilian oregano
- 1/4 cup (23g) finely grated Pecorino Romano
- 1/2 cup (120g) extra virgin olive oil divided
Seasoned breadcrumb mixture (mix together)
- 1/2 cup (50g) plain breadcrumbs
- 1 teaspoon Sicilian oregano
- 1/4 cup (23g) finely grated Pecorino Romano
- 1/2 teaspoon crushed hot red pepper flakes
- 3 tablespoons (45g) extra virgin olive oil
- 2 cloves garlic minced
Want To Save This Recipe?
Enter your email and we’ll send it to you. Plus, get great new recipes from us every week!
Instructions
- Preheat the oven to 375f and set the rack to the middle level. In a bowl, mix together the ingredients for the seasoned breadcrumbs and set aside.
- Use a mandoline or sharp knife to make thin slices of the zucchini (lengthwise), tomatoes, and onions. Drain the sliced tomatoes and pat dry both the tomatoes and zucchini with paper towels before the layering process.
- Oil a 9×13 baking dish. Place a few layers of zucchini then drizzle extra virgin olive oil and season with salt, pepper, oregano, and Pecorino Romano cheese. Next, add a few layers of onions and drizzle the olive oil and season in the same manner. Finally layer the tomatoes, drizzle the oil and season. Sprinkle the breadcrumbs on top and grate a bit more cheese. Drizzle more oil if required. The breadcrumbs should be well moistened.
- Bake for 45 minutes or until bubbly. Most of the liquid should be evaporated at this point. If the breadcrumbs aren't golden brown you can broil for the last 1-2 minutes but watch very carefully. Wait at least 10-15 minutes before serving so that the juices settle. Enjoy!
Notes
- A large shallow baking dish with only 3 layers works better and cooks quicker than a deep dish with many layers of ingredients, but both will work.
- Distribute a portion of the seasoning on each level. Depending on how many levels are made, a bit more or less seasoning might be required.
- Cooking times are a rough estimate. Bake until most of the liquid evaporates and the zucchini is clear and tender. If the casserole is wet after 45 minutes of baking you can carefully drain some of the liquid or pull it out with a bulb blaster or paper towels and bake for another 5-10 minutes before serving.
- For more browning, the dish can be broiled for the last 1-2 minutes, but watch carefully.
- Leftovers can be saved for up to 3 days and can be reheated in the oven or microwave.
Nutrition
Nutrition information is automatically calculated, so should only be used as an approximation.
Follow Me
The Sip and Feast Cookbook
- 100+ recipes
- Essential tools and ingredients
- Entertaining ides
- Stunning photography
This recipe is absolutely delicious
added the bottom layer of sliced russet potatoes.
This is a keeper.
Thanks
JoannE