This zucchini casserole is an easy vegetarian dish filled with fresh summer veggies, four kinds of cheese, and a crispy breadcrumb topping. Try it for Meatless Monday!
Ever find yourself wondering what to do with all your fresh summer produce? If so, this summer casserole is for you! It’s got layers of sweet onions, tangy tomatoes, salty cheese, and farm-fresh zucchini topped with a flavorful, crunchy parmesan bread crumb topping. This casserole is a great way to use the abundance of fresh summer produce.
I ran across this recipe a few weeks ago. I hadn’t made this zucchini casserole since David and I lived in Virginia Beach. It’s funny how recipes are like coming across old pictures. They can take you back to a different time and place.
Let me show you how to make this 4 Cheese Zucchini Casserole recipe!
An Easy and Versatile Casserole Recipe
Farm fresh zucchini is the star ingredient of this cheesy casserole. The zucchini slices are layered with tomatoes, onions, and three kinds of cheese with a crunchy parmesan panko breadcrumb topping.
Vegetables shine in this dish without heavy filling or sauce made of heavy cream or eggs. It’s deliciously flavorful and so versatile. It’s a great main dish recipe for Meatless Monday!
Ingredients You’ll Need To Make Zucchini Casserole
This recipe is very versatile. You can use different types of tomatoes, squash, and onions. Even the cheese can be swapped for what you have available, or choose the combination you like the best.
The recipe card at the end of this post provides a detailed list of ingredients.
Zucchini: the zucchini does not have to be peeled. You can also mix and match zucchini with yellow squash. Use whatever fresh produce you have.
Tomatoes: for best results, use fresh summer tomatoes. Any variety shape or size is fine.
Onion: I love using extra large Vidalia onions when they are in season. Vidalias produce beautiful extra-large onion rings that cook up sweet and tender like candy when sliced. Any onion you have on hand is ok to use in this casserole.
Salt: use kosher salt to draw the excess moisture out of the zucchini and tomatoes. Use regular table salt if that’s what you have.
Oil: use oil to grease the bottom of the casserole dish to keep the vegetables from sticking. I use extra-virgin olive oil, but use whatever you like. Even cooking spray is fine.
The Cheeses: I use grated extra-sharp cheddar for its flavor—shredded mozzarella cheese for its creamy melting ability, and feta for its salty bite. Use any combination of cheese you have on hand or like the best.
Fresh Herbs: Fresh thyme and basil compliment the vegetables making them extra bright and delicious. Thyme is used within the vegetable layers, and fresh basil is the garnish, making the casserole look pretty.
The Bread Crumb Topping: I use panko breadcrumbs to make the topping nice and crispy. You can also use plain breadcrumbs if you prefer. The parmesan cheese gives the casserole a salty bite, while the dried oregano adds an even more delicious earthy flavor.
Seasoning: Kosher salt and freshly cracked black pepper, to taste. Remember that the cheese and some salt are absorbed into the vegetables, so go easy on the salt.
How to Make Baked Zucchini Casserole
Detailed instructions are provided in the recipe card at the end of this post.
Salt The Tomatoes And Zucchini
If you wonder how to keep the zucchini from becoming watery, I have the answer: Salt!
Adding salt to the tomatoes and zucchini draws out excess moisture from the vegetables, a process called osmosis. Drawing the excess moisture out of the vegetable before they cook them gives them better texture and concentrates the flavor of fruits and vegetables.
- Salt the zucchini and tomatoes for at least 30 minutes before adding them to your casserole dish—Pat the zucchini dry with a clean kitchen towel or paper towel.
Assemble the Zucchini Casserole
- Drizzle the baking dish with olive oil, so the vegetables don’t stick.
- Layer half of the veggies into the casserole dish, and season with salt and pepper, to taste.
- Top with half of the cheddar, mozzarella, and feta cheeses. Sprinkle with ½ of the fresh thyme.
- Repeat to form a second layer of each.
Prepare the Breadcrumb Topping:
- In a small bowl, stir together the breadcrumbs, parmesan cheese, and oregano.
- Pour the bread crumb mixture over the layers of vegetables and cheese.
Bake the Casserole:
- Bake in the 350-degree oven for 55-60 minutes until the vegetables are tender and the cheese is melted and starts to brown.
- Turn the broiler on high and broil until the cheese and bread crumbs are dark golden brown, about 3-4 minutes.
Cool and Serve
- Remove from the oven and allow the Zucchini Bake to cool for 15 minutes before serving.
Tips For Making This Recipe
- Slicing: Slice all the vegetables to the same thickness for even uniform cooking.
- Salting the Vegetables: I highly recommend salting the zucchini and tomatoes before baking to keep the casserole from getting too watery. However, if you don’t have time, the casserole will still be delicious, but the texture will be a little sloppy.
- Leftovers: This casserole can be sealed in an airtight container in the refrigerator for up to three days. To reheat, either bake at 350 for 20-30 minutes or microwave for a minute or two.
- Adding Meat: If it’s not Meatless Monday, feel free to add some protein into the casserole, such as shredded rotisserie chicken or ground beef for the carnivores!
- Gluten-Free & Extra Low Carb: To make this casserole gluten-free, omit the panko bread crumbs and use parmesan cheese and oregano. Skipping bread crumbs will also make a low-carb recipe even lighter!
FAQs
I do not recommend freezing this casserole. Even though the vegetables are salted before baking to draw out excess moisture, they are still too watery to be frozen. It’s just too mushy to be appetizing after freezing. Freezing also makes the cheese weird.
Absolutely! Use any fresh summer vegetables you wish. Proceed to salt the yellow squash just like you would the zucchini.
I’m so glad I ran across the recipe again. This casserole is a delicious way to showcase fresh summer produce for the garden. It’s perfect as a Meatless Monday main course or a side dish for any meal. You can also add meat to make this a main dish.
4 Cheese Zucchini Bake
Ingredients
- 2 large tomatoes sliced ¼-inch thick
- 2 medium zucchinis sliced ¼-inch thick
- Kosher Salt
- 1 tablespoon Extra virgin olive oil
- 1 large Vandalia onion sliced ¼-inch thick
- 2 cups extra-sharp cheddar cheese shredded
- 2 cups mozzarella cheese shredded
- ½ cup feta cheese crumbled
- 2 tablespoons fresh thyme chopped
- Kosher salt and freshly cracked black pepper to taste
- Fresh Basil for serving (optional)
Bread Crumb Topping:
- ½ cup parmesan cheese grated + extra for topping (optional)
- ½ cup panko bread crumbs
- 1 tablespoon dried oregano
Instructions
- Slice the tomatoes and arrange the slices on a rack or onto paper towels. Sprinkle very lightly with salt on both sides. Set aside. Slice the zucchini and toss with salt inside a colander. Allow the tomatoes and zucchini to sit for at least 30 minutes to draws out the excess moisture.
- Meanwhile, slice the onions and gather the rest of the ingredients.
- Preheat the oven to 350 degrees F.
- After 30 minutes, blot the excess moisture off of the tomatoes with a paper towel. Rinse the zucchini slices and drain. Blot well or put them in a salad spinner to dry the zucchini slices.
- Drizzle the olive oil into the bottom of a 9×13 baking dish. Layer half of the zucchini, tomato, and onion slices into the baking dish. Top with half of the cheddar, mozzarella, and feta cheeses. Sprinkle with ½ of the fresh thyme. Repeat to form a second layer of each.
- In a small bowl, mix together the breadcrumbs, parmesan cheese, and oregano. Top the layers of vegetables and cheese with the bread crumb topping.
- Bake in the 350-degree oven for 55-60 minutes until the vegetables are tender and the cheese is melted and starts to brown. Then turn the broiler on high and broil until the cheese and bread crumbs are dark golden brown, about 3-4 minutes.
- Remove from the oven and allow the Zucchini Bake to cool for 15 minutes before serving with fresh basil and extra parmesan cheese.
Notes
- Slicing: Slice all the vegetables to the same thickness for even uniform cooking.
- Salting the Vegetables: I highly recommend salting the zucchini and tomatoes before baking to keep the casserole from getting too watery. However, if you don’t have time, the casserole will still be delicious, but the texture will be a little sloppy.
- Leftovers: This casserole can be sealed in an airtight container in the refrigerator for up to three days. To reheat, either bake at 350 for 20-30 minutes or microwave for a minute or two.
- Adding Meat: If it’s not Meatless Monday, feel free to add some protein into the casserole, such as shredded rotisserie chicken or ground beef for the carnivores!
- Gluten-Free & Extra Low Carb: To make this casserole gluten-free, omit the panko bread crumbs and just use parmesan cheese and oregano. Omitting bread crumbs will also make a low-carb recipe even lighter!
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