This easy Zucchini Casserole recipe brings together fresh zucchini, cheese, and a handful of simple ingredients to create a comforting and nutritious dish! It’s an easy side dish that pairs perfectly with a variety of main courses, and it’s great flavor will be a hit with the whole family!
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We grow zucchini in our garden every summer, and we always end up with more zucchini than we can use in zucchini bread alone. Even though we share with anyone who will take it, we still sometimes end up with more zucchini than we know what to do with!
This old fashioned zucchini casserole recipe is delicious way to enjoy and use up lots of zucchini, especially if you’re growing it in your garden during the summer months. The combination of cheeses – Gruyere, mozzarella, and Parmesan – creates a rich and creamy texture that’s hard to resist, and the toasted Panko breadcrumbs add a delightful crunch to every bite.
The whole family loves this dish and when I serve it to guests, it’s often the most popular thing on the table! It goes with all kind of proteins from grilled chicken or pork tenderloin to baked salmon and is right up there with Southern tomato pie and corn fritters for being one of my favorite summer vegetable recipes.
For more of my best zucchini recipes, check out my Zucchini Fries, Zucchini Salad, Zucchini Brownies with Chocolate Icing, Lemon Poppy Seed and Zucchini Bread, and Zucchini Noodles (AKA Zoodles)!
Why We Love This Recipe
- This parmesan zucchini casserole recipe is a great way to introduce more vegetables into your diet in a delicious way. Plus it’s naturally low-carb.
- You can serve it as a main dish or as a hearty side – it pairs well with chicken, beef, or even as part of a vegetarian meal.
- A few common kitchen tools and simple ingredients are all you need to create this delightful zucchini bake recipe.
What You’ll Need
Scroll down to the recipe card below this post for ingredient quantities and full instructions.
- Fresh Zucchini – The star of the dish, providing a tender and slightly sweet base.
- Kosher Salt – Used to draw out moisture from the zucchini, enhance the zucchini’s overall flavor, and season the sauce.
- Melted Butter – Adds richness and helps toast the Panko breadcrumbs.
- Sweet Onion – Brings a subtle sweetness and depth of flavor.
- Minced Garlic Cloves – Adds a wonderful aromatic element.
- Heavy Cream – Contributes to the creamy sauce.
- Dried Basil – Provides a hint of herbal flavor.
- Onion Powder – Enhances the onion flavor.
- Dried Thyme – Adds a subtle earthiness.
- Dried Oregano – Brings a touch of Mediterranean flavor.
- Black Pepper – Adds a bit of heat and complexity.
- Shredded Gruyere Cheese – Offers a nutty and creamy texture.
- Sour Cream – Adds tanginess and creaminess.
- Shredded Mozzarella Cheese – Melts beautifully for a gooey texture.
- Freshly Grated Parmesan Cheese – Adds a sharp and salty finish.
- Panko Breadcrumbs – Provides a crispy topping.
How to Make Cheesy Baked Zucchini Casserole
- Prepare zucchini slices. Preheat oven to 400°F. Start by tossing the zucchini slices with 2 teaspoons of kosher salt in a large bowl. Spread the zucchini out in an even layer on a baking sheet lined with paper towels. Let it rest for 15 to 30 minutes to allow the water to leech out. Pat the zucchini dry with a clean dish towel and brush off any excess salt.
- Saute onion and garlic. While the zucchini rests, melt 1 Tablespoon of butter in a large pan over medium-high heat. Add the sliced onions and sauté for 5-7 minutes until softened. Add the minced garlic and sauté for another 30 seconds.
- Add cream and seasonings. Stir in the heavy cream, dried basil, onion powder, thyme, oregano, ½ teaspoon of kosher salt, and black pepper. Bring the mixture to a simmer for about 3 minutes, then remove from the heat.
- Add sour cream and cheese. Stir in the sour cream and ¾ cup of the shredded Gruyere cheese until melted.
- Assemble casserole. Arrange half of the zucchini slices in the bottom of a 2-quart baking dish or casserole dish, allowing them to overlap slightly. Spoon half of the onion and sauce mixture over the zucchini.
- Complete assembly and bake. Add another layer of zucchini and the remaining sauce. Sprinkle the remaining ¼ cup of Gruyere cheese, mozzarella cheese, and Parmesan cheese on top. Cover with foil and bake for 30 minutes.
- Prepare breadcrumbs. While the casserole bakes, melt the remaining 2 Tablespoons of butter in a pan. Add the Panko breadcrumbs and toast over medium heat until golden brown.
- Add breadcrumbs and finish baking. After 30 minutes, remove the foil from the casserole and sprinkle the toasted breadcrumbs on top. Bake uncovered for another 5 minutes. Let the casserole rest for 5-10 minutes before serving.
Recipe FAQ’s
Yes, summer squash works just as well and adds a lovely yellow color variation to the dish.
Consider adding cooked ground beef or cooked, sliced chicken breasts to the casserole layers for extra protein if you are looking to make this a main dish.
Absolutely. You can prepare the casserole up to the baking step, cover it, and refrigerate it for up to a day before baking.
Store any leftover cheesy zucchini casserole in an airtight container. It will keep well in the refrigerator for up to 3-4 days. Ensure the casserole is completely cooled before covering it to prevent condensation and sogginess.
While it’s best enjoyed fresh, you can freeze leftovers in an airtight container for up to 2 months. Thaw in the refrigerator overnight before reheating.
Tips for Success
- Salting the zucchini slices is crucial to draw out excess water and prevent a watery casserole. Be sure to let the zucchini rest with the salt for at least 15 minutes and then pat them dry thoroughly.
- When assembling the casserole, try to layer the zucchini and sauce evenly. This ensures that every bite is packed with flavor and that the casserole cooks uniformly.
- Using a combination of Gruyere, mozzarella, and Parmesan cheese gives the casserole a rich, complex flavor. However, feel free to experiment with other cheeses like cheddar or fontina based on your preference.
- Toasting the Panko breadcrumbs in butter before adding them to the casserole adds a wonderful crunch. Make sure they are golden brown before sprinkling them on top to achieve the best texture.
What To Serve With Cheesy Zucchini Bake Casserole
The creamy texture and savory flavors of this cheesy zucchini casserole pair well with various proteins, such as grilled chicken breasts, baked salmon, or a juicy steak.
A crisp, fresh salad is a great side dish to balance the richness of the casserole. Consider a simple green salad with a light vinaigrette or a tangy Greek salad with tomatoes, cucumbers, olives, and feta cheese.
To add more variety, serve this casserole with roasted or steamed vegetables. Broccoli, asparagus, or green beans are excellent choices that add both color and nutrition to your meal.
A slice of crusty bread or a soft dinner roll makes a great accompaniment, perfect for mopping up any extra creamy sauce. Garlic bread or herbed focaccia are particularly delicious options.
Substitutions and Variations
- Substitute zucchini with yellow squash, or make zucchini squash casserole by taking a half-and-half approach and using both for added color and flavor.
- Swap Gruyere cheese with Swiss cheese or a sharp white cheddar if Gruyere is unavailable.
- Greek yogurt can be used instead of sour cream as a healthier alternative.
- Regular breadcrumbs or crushed crackers can be used as a substitute for Panko breadcrumbs.
- If you have fresh herbs on hand, use them instead of dried herbs for a more vibrant flavor.
- For a low-carb option, skip the breadcrumbs or use a low-carb breadcrumb alternative like almond meal.
Cheesy Zucchini Casserole Recipe
Ingredients
- 2 pounds zucchini, sliced into 1/4-inch thick rounds
- 2 teaspoons kosher salt
- 3 tablespoons melted butter, divided
- 1 medium sweet onion, sliced
- 4 cloves garlic, minced
- 1 cup heavy cream
- 1 ½ teaspoons dried basil
- 1 teaspoon onion powder
- ½ teaspoon dried thyme
- ½ teaspoon dried oregano
- ½ teaspoon kosher salt
- ½ teaspoon black pepper
- 1 cup shredded Gruyere cheese (about 3 ounces), divided
- ½ cup sour cream
- ⅔ cup shredded mozzarella cheese
- ¼ cup freshly grated Parmesan cheese
- ½ cup Panko breadcrumbs
Instructions
- Preheat oven to 400°F. Toss zucchini with salt in a large bowl, then spread out in an even layer on a baking sheet lined with paper towels. Let rest for 15 to 30 minutes to allow water to leech out of the zucchini. Pat dry and brush off the salt from the sliced zucchini.2 pounds zucchini,, 2 teaspoons kosher salt
- Meanwhile, melt 1 Tablespoon of the butter in a large pan over medium-high heat. Add sliced onions and saute for 5-7 minutes until softened. Add garlic and saute for another seconds.3 tablespoons melted butter,, 1 medium sweet onion,, 4 cloves garlic,
- Add heavy cream, dried basil, onion powder, thyme, oregano, salt, and pepper to the sauteed onions in the pan. Bring to a simmer for about 3 minutes. Remove the pan from the heat and stir in the sour cream and ¾ cup of the gruyere cheese until melted.1 cup heavy cream, 1 ½ teaspoons dried basil, 1 teaspoon onion powder, ½ teaspoon dried thyme, ½ teaspoon dried oregano, ½ teaspoon kosher salt, ½ teaspoon black pepper, 1 cup shredded Gruyere cheese, ½ cup sour cream
- Arrange half of the zucchini in the bottom of a 2-quart baking dish. It's okay for them to overlap. Spoon half of the onions and sauce over the zucchini. Layer the remaining zucchini and sauce. Sprinkle the remaining ¼ cup gruyere cheese, mozzarella cheese, and Parmesan cheese on top. Cover with foil and bake 30 minutes.¼ cup freshly grated Parmesan cheese, ⅔ cup shredded mozzarella cheese
- While the casserole bakes, melt the remaining 2 Tablespoons of butter in another pan. Add the Panko breadcrumbs and toast over medium heat until golden brown.½ cup Panko breadcrumbs
- Remove the foil covering the casserole and sprinkle with the toasted breadcrumbs. Bake uncovered for 5 minutes. Let rest 5-10 minutes before serving.
Notes
Storage & Make Ahead
- Make Ahead: Prepare the casserole up to the baking step, cover it, and refrigerate for up to a day before baking.
- Store: Store leftover cheesy zucchini casserole in an airtight container in the refrigerator for up to 3-4 days.
- Freeze: Freeze leftovers in an airtight container for up to 2 months. Thaw in the refrigerator overnight before reheating.
Nutrition
More Casserole Recipes You’ll Love
- Amazing Sausage and Rice Casserole
- Creamy Chicken Noodle Casserole
- Chicken and Stuffing Casserole
- Easy Chili Relleno Casserole
- Easy Chicken Cordon Bleu Casserole
- Sweet Potato Casserole with Marshmallows
- Pepperoni Casserole (Pizza Bake Recipe)
- Tuna Noodle Casserole
DEELICIOUS!!! Reminded me of a recipe my sister-in-law has made but she never remembers what she puts in it and I haven’t been able to recreate it, until now! Thanks!
We love zucchini and I’m always looking for new recipes. This one was so good with the cheese blends and crunchy bread crumbs.
Thank you! I love zucchini as well!
My garden runneth over with zucchini and this casserole was a big win!! Thank you for sharing this! It was so good!!!
Oh wow so lucky you already have zucchini! I’m glad you found this recipe to use up all that delicious zucchini!