A fresh zucchini casserole with sautéed onions and garlic in a creamy cheese sauce topped with buttery Parmesan Panko breadcrumbs. This popular casserole brings out the best in summer zucchini and makes a great side dish for grilled chicken, fish, steak, and pork tenderloin, along with baked potatoes or rice.
How to make zucchini casserole
First, heat a little olive oil in a large skillet over medium-high heat. Then add the onion and cook until soft. Reduce the heat to low and add the garlic, cooking for 1 minute while stirring constantly. Plate the vegetables. Heat a little more olive oil in the skillet over high heat until it sizzles when the zucchini touches it. Add the zucchini and cook just until very lightly browned, stirring a couple of times. Plate the zucchini.
Reduce the heat to medium. Using the same skillet, melt the butter. Once melted, whisk in the flour. Cook for 2 minutes while whisking constantly. Slowly add the milk while whisking. Whisk in the salt, black pepper, and nutmeg and cook until thickened. Reduce the heat to low and whisk in the cheddar cheese a little at a time until melted.
Meanwhile, in a small bowl, combine the butter, Panko bread crumbs, and Parmesan Cheese. Add the veggies to a 2 1/2 quart baking dish. Pour the cheese sauce over the veggies and stir to coat. Sprinkle with the panko breadcrumb mixture. Finally, bake for 25-30 minutes or until lightly browned and bubbly.
Recipe notes and helpful tips
- The zucchini is cooked on high in the skillet just long enough to cook most of the moisture off and prevent a watery casserole. You don’t want to cook it tender because you are going to bake it.
- This recipe works well with yellow squash too.
- For best results, use medium zucchini. The larger zucchinis can be tough, so it is best to avoid them.
- You can slice it into rounds, but I quarter it first and then slice zucchini at about 1/3-1/2 an inch.
- Nutmeg adds just a touch of sweetness, but if you don’t like nutmeg, try something more savory, like marjoram or thyme.
- If a little added flavor or kick is desired, add a little crushed red pepper, cayenne pepper, or creole seasoning.
- Garnish the casserole with chopped fresh parsley or thyme.
- This casserole is best enjoyed fresh out of the oven while warm and melty.
- Store leftovers in an airtight container in the refrigerator for up to 3 days.
- I do not recommend freezing this casserole. The amount of water in the zucchini combined with the béchamel cheese sauce will separate.
How to salt zucchini
You can skip the cooking of the zucchini and salt it instead. Add the chopped zucchini in layers to a colander salting each layer as you go. Let it drain for about 30 minutes, and then proceed with the rest of the recipe. There is no need to cook the zucchini. However, bake the casserole for 30-35 minutes. Cover the dish with aluminum foil if the casserole browns too fast.
More zucchini recipes to try!
Zucchini Casserole
Ingredients
- 2 tablespoons olive oil
- 1 medium yellow onion chopped
- 2 cloves garlic
- 8 cups chopped zucchini
- 4 tablespoons butter
- ¼ cup flour
- 2 ½ cups milk
- 1 teaspoon salt
- ½ teaspoon fresh ground black pepper
- ¼ teaspoon nutmeg
- 2 cups finely shredded cheddar cheese
- 3 tablespoons melted butter
- 1 cup panko breadcrumbs
- ½ cup grated fresh Parmesan cheese
Instructions
- Preheat oven to 375 degrees. Spray a 2 1/2 quart casserole with nonstick cooking spray.
- Heat 1 tablespoon olive oil in a large pan over medium-high heat. Add the onion and cook until soft. Reduce the heat to low and add the garlic, cooking for 1 minute while stirring constantly. Plate the vegetables.
- Heat the other tablespoon of olive oil in the skillet over high heat until it sizzles when the zucchini touches it. Add the zucchini and cook just until very lightly browned, stirring a couple of times. Plate the zucchini.
- Reduce the heat to medium. Using the same skillet, melt the butter. Once melted, whisk in the flour. Cook for 2 minutes while whisking constantly. Slowly add the milk while whisking. Whisk in the salt, black pepper, and nutmeg and cook until thickened. Reduce the heat to low and whisk in the cheddar cheese 1/2 cup at a time until melted.
- Meanwhile, in a small bowl, combine the butter, Panko breadcrumbs, and Parmesan Cheese. Add the zucchini mixture to the prepared casserole dish. Pour the cheese sauce over the zucchini mixture and stir to coat. Sprinkle with the panko breadcrumb mixture. Bake for 25-30 minutes or until lightly browned and bubbly.
Notes
- The zucchini is cooked on high in the skillet long enough to cook most of the moisture off and prevent a watery casserole. You don't want to cook it tender because you will bake it.
- This recipe works well with yellow squash too.
- For best results, use medium zucchini. The larger zucchinis can be tough, so it is best to avoid them.
- You can slice it into rounds, but I quarter it first and then slice zucchini at about 1/3-1/2 an inch.
- Nutmeg adds just a touch of sweetness, but if you don't like nutmeg, try something more savory, like marjoram or thyme.
- If a little added flavor or kick is desired, add a little crushed red pepper, cayenne pepper, or creole seasoning.
- Garnish the casserole with chopped fresh parsley or thyme.
- This casserole is best enjoyed fresh out of the oven while warm and melty.
- Store leftovers in an airtight container in the refrigerator for up to 3 days.
- I do not recommend freezing this casserole. The amount of water in the zucchini combined with the béchamel cheese sauce will separate.
Nutrition
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Kimberlee
Love your food, Beth
Beth Pierce
Thanks, Kimberlee!
Michelle
Love this comforting way of using up all that summer garden fresh zucchini
Catalina
I can’t resist this casserole! I love zucchini so much and I make this very often during the summer! So tasty!
Erin
You had me on this! Definitely a must make!
Beth Pierce
Thanks! Enjoy!!
Amanda
This has been our favorite zucchini recipe all summer! Even my kids love it.
Beth Pierce
Thanks! That is saying something when kids like it!
Erik
Perfect for the zucchini I just got. Such perfect combination of summer flavors!
Tayler
I made this with dinner last night and it was incredible! A great way to use up zucchini from my garden!
Beth Pierce
Thanks Tayler. It is that time of the year again when zucchini is extremely abundant.
Jessie
This is a PERFECT recipe for all that summer zucchini. I love that it’s cozy and creamy but still very summery – perfect with a big salad! I also had all these ingredients in the pantry already, which makes it an automatic win in my book.
Beth Pierce
Thanks Jessie! Enjoy! It is always a win win when you have the ingredients ready to go.
Nikki
My friend shared zucchini from her garden and this was just the thing to make. Cheesy with that crunchy topping and the family gobbled this right up! Delish.
Beth Pierce
Thanks Nikki! So happy to hear that you and the family liked it!
Amanda Wren-Grimwood
I’ve been looking for another zucchini dish as my garden is overflowing. So creamy and delicious.
Lyn
This looked so amazing I just had to made it! Came out perfectly. Thank you.
Beth Pierce
The pleasure is all mine Lyn! Glad that you enjoyed it!
Juliane
This is heaven sent! The best I have tasted so far!
Beth Pierce
Thanks Juliane! So glad that you liked it!
Sandra
I love zucchini and this one is my new favorite! So good!
Beth Pierce
Thanks Sandra!
Kelley
This was such a delicious recipe to use up zucchini from our garden! Thank you!
Tayler Ross
My garden is overflowing with zucchini, so I can’t wait to make this casserole! Adding it to our dinner list this week!
Tavo
Such a tasty zucchini casserole. I love that it was super cheesy and flavor-packed!