The Cozy Cookbook is here! 
This easy Zucchini Casserole is the best way to make use of fresh garden zucchini. The flavorful filling is cheesy and perfectly seasoned, eggs bind everything together and add protein, and panko breadcrumbs add the perfect crunch. Don’t miss out on this recipe!
Be sure to try my Zucchini Soup and Eggplant Casserole recipes next!
Zucchini Casserole
I honestly can’t be trusted around this Zucchini Casserole, one small bite leads to 100 small bites. (You’ve been warned!) I thought that Zucchini Soup was my favorite way to enjoy garden zucchini, but this casserole is a fierce competitor!
The filling is perfectly seasoned, cheesy, (not the least bit watery), with eggs that act as a binder while also adding protein, and panko breadcrumbs that add the best texture. You really can’t beat this recipe!
Be sure to check out my pro tips below!
How to Make It
Note: This is an overview. See recipe card below this post for ingredient quantities and full instructions.
Shred the zucchini and transfer to a colander. Sprinkle with salt and top with paper towels while you prepare the remaining casserole ingredients. Squeeze out excess water and transfer the zucchini to a mixing bowl along with sauteed onions, garlic, Parmesan, Panko, heavy cream, eggs, Dijon, and seasonings. Stir to combine.
Transfer the filling to a lightly greased casserole dish and top with cheddar cheese. Cover and bake at 375° F for 30 minutes.
Combine melted butter and panko breadcrumbs and sprinkle it over the casserole. Bake uncovered 15 minutes. Broil at 425° F for 1-2 minutes to brown the top more if preferred. Let it sit for 5 minutes, then serve!
Pro Tips
- You can leave the skin on the zucchini unless it’s jumbo sized, in which case the skin may be bitter.
- Yellow squash can be used in combination with the zucchini in this casserole.
- Gruyere cheese can be used along with the Parmesan cheese.
- It’s best to bake right after assembling as opposed to making this ahead of time, as the zucchini will continue to release water upon being salted.
- 4 medium zucchini is enough to produce 9 cups shredded.
- Shred the cheese from a block for best flavor and meltability. I use Belgioioso Parmesan and Cracker Barrel Sharp Yellow Cheese.
- Optional Additions: Finely shredded carrots, sauteed mushrooms and/or peppers, or even some cooked ground sausage make nice add-ons to this casserole. I would add an extra egg for additional binding if you add more ingredients to this dish.
- For more zucchini recipes, try my Zucchini Soup, Zucchini Parmesan, and Zucchini Crust Pizza! And be sure to try my Eggplant Casserole recipe.
Storage
- Store in an airtight container and refrigerate for up to 3 days (leftovers are even good cold!) or freeze for up to 3 months. I do enjoy freezing and reheating leftovers.
- Reheat leftovers in a lightly greased, uncovered casserole dish at 350° for 20-25 minutes or until heated through.
Tools For This Recipe
(Amazon affiliate links*)- Check out all of my kitchen essentials here.
- 9 x 13-inch Casserole Dish
- Box Cheese Grater– Perfect for shredding the zucchini and the cheese, this is the one I have.
- Large Measuring Cups– Great for measuring the shredded zucchini.
- Colander– I have this one and it’s great.
- Spice Rack–This is the one I have, it’s a snap to measure out your seasonings quickly and easily. (Big time saver.)
- Measuring Spoons– I have these magnetic ones which stay nice and organized in my utensil drawer.
- Mixing Bowls
- Silicone Spatulas– Perfect for mixing and handling the casserole filling throughout assembly.
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Try These Next
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- Peach Chicken
-
- Peach Cobbler
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- Apple Pork Chops
-
- Eggplant Casserole
-
- Zucchini Soup
-
- Egg Roll in a Bowl
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Tried This Recipe?
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Zucchini Casserole
Ingredients
Filling
- 9 cups shredded zucchini, about 2 ½ lbs. whole zucchini
- 1 ½ teaspoons salt
- 2 teaspoons olive oil
- 1 small yellow onion, finely diced
- 3 cloves garlic, minced
- 3 large eggs, whisked
- ¼ cup heavy cream
- 1 teaspoon Dijon mustard
- 1 ¼ cup panko breadcrumbs
- 1 cup shredded Parmesan cheese
- ½ teaspoon EACH: oregano, basil, garlic salt, parsley
- ¼ teaspoon EACH: paprika, black pepper
- 1 ¼ cups shredded cheddar cheese, for the top of the casserole
Breadcrumb Topping
- ¼ cup panko breadcrumbs
- 1 tablespoon butter, melted
Instructions
- Preheat oven to 375° F.
- Shred the zucchini (with the skin on unless jumbo sized, see notes) and transfer it to a colander. Sprinkle with a light layer of salt, I use 1 ½ teaspoons. Top with paper towels and let sit for 15 minutes (or longer) while you measure out remaining ingredients.
- Heat olive oil in a small skillet over medium heat. Add the onions and soften for 5 minutes. Add the garlic and soften for 2 minutes. Remove and set aside.
- Use paper towels to press down and absorb all excess moisture from the zucchini. Not so much that you have no zucchini left, but enough so that it's not excessively wet. (Note: This is a forgiving recipe. I have removed too much liquid before, and also not quite enough- it's always amazing either way. It sets more as it stands after baking as well.)
- Transfer to a large bowl along with the sauteed onions and garlic, whisked eggs, heavy cream, Dijon, 1 ¼ cup panko, parmesan cheese, and seasonings. Stir to combine.
- Transfer to a lightly greased 9 x 13-inch casserole dish. Top with cheddar cheese.
- Cover and bake for 35 minutes.
- Combine the 1/4 cup panko and melted butter for the topping and sprinkle it over the casserole. Bake uncovered for 15 minutes. If desired, broil at 425 for 1-2 minutes to add more color to the top. Watch it carefully during this time.
- Remove and let stand for 5 minutes prior to serving.
Notes
- You can leave the skin on the zucchini unless it's jumbo sized, in which case the skin may be bitter.
- Yellow squash can be used in combination with the zucchini in this casserole.
- Gruyere cheese can be used along with the Parmesan cheese.
- It's best to bake right after assembling as opposed to making this ahead of time, as the zucchini will continue to release water upon being salted.
- 4 medium zucchini is enough to produce 9 cups shredded.
- Shred the cheese from a block for best flavor and meltability. I use Belgioioso Parmesan and Cracker Barrel Sharp Yellow Cheese.
- Optional Additions: Finely shredded carrots, sauteed mushrooms and/or peppers, or even some cooked ground sausage make nice add-ons to this casserole. I would add an extra egg for additional binding if you add more ingredients to this dish.
- For more zucchini recipes, try my Zucchini Soup, Zucchini Parmesan, and Zucchini Crust Pizza! And be sure to try my Eggplant Casserole recipe.
Storage:
- Store in an airtight container and refrigerate for up to 3 days (leftovers are even good cold!) or freeze for up to 3 months. I do enjoy freezing and reheating leftovers.
- Reheat leftovers in a lightly greased, uncovered casserole dish at 350° for 20-25 minutes or until heated through.
Nutritional information is an estimate and is per serving. This recipe makes 8 servings.
wonderful summer side! I even missed an instruction and I mixed the cheddar cheese in with a zucchini mixture and it’s still turned out great!
* I also use milk instead of cream because I didn’t want to buy a carton for just a 1/4 of a cup
Nice work Tracy!!! I’m so happy you liked it! I’m addicted to this, I made it 3 times in the past 2 weeks. Thanks so much for the great comments!💖
Oh my God, this was super fantastic. I will be making it again. Elevates zucchini to the next level. Thank you for another great recipe. Your #1 fan!!!!!
Nice work Carol! Thanks so much for your support, you’re amazing!❤️
I’m going to give this recipe five stars. I followed it exactly with the addition of one large tomato and an extra egg. I just have a lot of tomatoes I need to use up. I had my doubts because the batter was so thick initially and it spread very thin on the bottom of the 9 x 13 pan. I baked it for 35 minutes and then uncovered it, added the Panko with butter and baked it for 15 more minutes on the top shelf. I did not put it on broil and the sides and bottom were beautifully colored and the cheese on top also turned a gorgeous color. It Is delicious. I was concerned there wouldn’t be enough Panko on top with only a quarter of a cup but it was the perfect amount of crunch. The only thing I will do different next time is not at the garlic salt but using an extra clove of fresh garlic and regular salt. Garlic powder has a distinct flavor that stands out a bit in this dish. This is wonderful comfort food and a great way to use up your zucchini. Thank you for an amazing recipe.
Hi Colleen! I’m so glad that you enjoyed this casserole!!! 🙂 The thickness of the filling can vary and depends on exactly how much water is removed from the zucchini, as that has a direct impact on the overall volume. Before publishing, I tested once by removing a lot of water, (resulting in a thin layer like yours), and removing far less (resulting in a much thicker layer)- I really enjoyed it both ways, which made me confident in its flexibility! It can be tough to cook/bake with veggies containing so much water. I really appreciate you taking the time to leave a review, thank you!!
This looks delicious! I am planning on making it and would like to freeze some as well. The frozen casserole works already be cooked, correct? Any idea how long to reheat it once thawed? Thanks!
Thank you Maria! Yes, I freeze leftovers after it’s already been baked. To reheat it I just let it thaw (overnight or on the “thaw” setting in the microwave), and then bake in an uncovered casserole dish at 350 for about 25 minutes or so! 🙂
I’m excited to try this recipe after I visit the local farmers market this week. I see you said it was freezable after being prepared. What is the best way to reheat it? Do you add anything to the leftovers? I appreciate all your delicious recipes that you post! Thank you 👐🏼
Hi Sam! I’m excited for you to try it as well! To reheat it I just let it thaw (overnight or on the “thaw” setting in the microwave), and then bake in a uncovered casserole dish at 350 for about 25 minutes or so! 🙂 I don’t typically add anything else to it when I reheat it.
I am sorry, I can’t find the breakdown of a cup of Panko for what goes into the zucchini and what goes on top?
Hi Amy! The headers indicate what ingredients go where. The first header says “filling” – that includes 1 + 1/4 cup of breadcrumbs. There is a another header that says “topping”, and that has 1/4 cup of panko breadcrumbs.
I sautéed 2 Yukon gold potatoes to the mixture, topped it with the panko cheese combo and baked as directed. It was delicious, try it you won’t be disappointed.
I’m so glad that you loved it Jeanne! Just thrilled to hear it!! Thank you so much for taking the time to leave a review, I really appreciate it! 🙂 -Stephanie