This Zucchini Casserole is pure comfort—layered rounds of tender zucchini baked in a rich cheddar cheese sauce and topped with crisp, buttery panko. It’s the kind of side dish that steals the spotlight, with just the right balance of creamy, cheesy, and crunchy. Serve it up for summer dinners, holiday spreads, or anytime you want to use up leftover zucchini.
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Say "goodbye" to boring vegetable side dishes with this baked zucchini casserole! One bite of this cheesy and garlicky indulgent dish and your any memories of boiled zucchini will vanish from mind. Tender slices of the vegetable are coated in a silky and luxurious white cheddar cheese sauce and sprinkled with buttery and crunchy breadcrumbs for a side dish that sets a new culinary precedent.
Though this dish does call for a few steps, they are quicker and easier than you may expect and—most importantly—are worth any extra effort and intention you invest. The result is a golden brown and bubbling zucchini bake fit for everything from weeknight dinners to potlucks, celebratory meals, and holiday feasts.
For more impressive vegetable side dish recipes, check out my Scalloped Sweet Potatoes, Creamed Peas, and Bread Pudding with Mushrooms & Butternut Squash.
Why You'll Love Zucchini Casserole
- Full Savory & Cheesy Flavor: Sharp white cheddar cheese elevates classic cheese sauce to new heights. It's further enhanced with sautéed garlic, sliced green onions, and grated nutmeg for a well-rounded and balanced flavor that complements the neutral-flavored zucchini like a dream.
- Crunchy & Buttery Topping: Flaky panko breadcrumbs are tossed with melted butter, creating a crunchy topping and adding texture.
- Versatile: You can make this zucchini bake recipe year-round and serve it with almost any main dish, adding it to the rotation along with other green vegetable side dishes.
- Perfect for Late Summer Produce: Though I love zucchini bread and zucchini cake as much as the next person, daily late summer zucchini harvests call for a selection of sweet and savory ways to enjoy the abundant veggie. This recipe sits at the top of my zucchini side dish list.
- Impressive & Festive: A bubbling sauce and crisp golden brown breadcrumb topping elicit oohs and ahhs from dinner guests, adding a special element to even weeknight meals, but also ideal for holiday meals, such as Easter or Christmas.
Ingredients
Zucchini: Choose squash with deep green and smooth skin that are dense and heavy for their size. You can use all zucchini like I did or make a squash casserole by using half zucchini and half yellow squash.
Green Onions: Adds peppery and lightly caramelized notes to the cheese sauce. Clean them well and chop the white and green portions of the onions.
White Cheddar Cheese: Sharp white cheddar cheese makes the sauce tangy and robust, perfect for the mellow and lightly-sweet zucchini. Opt for an aged white cheddar if possible, though sharp white is also great.
Milk: The luscious base for the cheese sauce. For the fullest flavor, use whole milk, though 2% also works in a pinch.
All-Purpose Flour: This helps absorb the moisture from the zucchini and thicken the cheese sauce. You will only need 3 tablespoons.
Unsalted Butter: Forms the base of the sauce and helps the breadcrumbs crisp up, making them perfectly crunchy.
Garlic: Adds nutty undertones to the dish, balancing the cheese's sharpness and enhancing the flavor of the zucchini. Chop garlic fresh if possible, though pre-minced bottled garlic can work if necessary.
Seasonings: Salt accentuates the cheddar sauce. Grated nutmeg elevates it, adding a comforting and rich finish inspired by the Italian practice of adding it to cheese sauces.
Panko Breadcrumbs: This is tossed with melted butter and grated parmesan cheese, creating a crunchy and buttery casserole topping when baked. Choose panko for the crispiest topping, though traditional breadcrumbs can work if needed.
Parmesan Cheese: Grated cheese mixes with the panko well, enhancing the savory cheesiness of the dish.
How to Make Zucchini Casserole
For the complete recipe and measurements, scroll to the recipe card at the bottom of this post.
Step 1: Preheat the oven to 375°F. Spray an 8 x 8-inch baking dish with nonstick cooking spray.
Step 2: Add the zucchini slices to a mixing bowl. Sprinkle with 4 teaspoons of all-purpose flour and toss until the zucchini is coated evenly with the flour.
Step 3: Lay half the floured zucchini slices in the pan, evenly overlapping them. Sprinkle with half of the green onions. Repeat with the remaining zucchini slices and green onions.
Step 4: Melt 2 tablespoons of unsalted butter in a saucepan over medium heat until foaming. Add the minced garlic and cook for 1-2 minutes until fragrant and lightly golden.
Step 5: Stir in the remaining all-purpose flour, cooking it for 1-2 minutes or until absorbed into the butter, bubbling, and smelling nutty.
Step 6: Pour in the milk. Stir or whisk well as it cooks for 3-5 minutes until the mixture has thickened.
Step 7: Reduce the heat to low and stir or whisk in the cheddar cheese, salt, and nutmeg until smooth and combined. Remove the saucepan from the heat.
Step 8: Pour the cheese sauce over the zucchini and green onions and spread it out evenly so it can seep down around the vegetables.
Step 9: Toss the melted unsalted butter, panko breadcrumbs, and parmesan cheese together in a small bowl until combined.
Step 10: Sprinkle the breadcrumb mixture over the cheese sauce. Top with freshly cracked pepper if desired. Bake in the oven for 30 minutes or until bubbly and the breadcrumb topping is golden. Let sit for 5-10 minutes before serving, allowing the sauce to thicken.
Recipe Pro-Tips
How to slice the zucchini. It can be helpful to slice the zucchini with a mandoline or food processor with a slicing attachment. Otherwise, you can slice with a chef’s knife, being careful to uniform pieces.
Let the casserole rest for 5-10 minutes before serving. This allows the sauce to thicken up, enhancing the texture and luxuriousness of the white cheddar sauce.
Doubling the recipe. Be the star of the potluck or family dinner by making a double batch! Double the ingredients and follow the recipe directions, baking the casserole in a 9x13-inch pan and increasing the baking time by 5-10 minutes until the cheese sauce bubbles and the topping is golden.
Recipe Variations
- Mixed Squash Casserole: Use any combination of 3 medium-sized yellow or summer squash, light green zucchini, or patty pan squash. If using patty pan squash, substitute 2 squash for 1 medium-sized zucchini.
- Sharp Cheddar Cheese Sauce: Use shredded sharp cheddar cheese instead of white for a more classic cheese sauce experience.
- Extra Veggies: Use up extra produce by layering in 2 small sliced tomatoes or 1 cup of wilted spinach before topping with the cheese sauce.
- Gluten-Free: If desired, make this dish gluten-free. Substitute 1-to-1 gluten-free flour for all-purpose flour and gluten-free or rice panko for traditional, and follow the recipe directions as listed.
Serving Suggestions
Aside from being a fantastic way to make the most of our late summer zucchini harvest, one of my favorite things about this zucchini casserole recipe is its versatility! Not only does farm-fresh zucchini shine in it, but it's a delicious way to enjoy the vegetable year-round.
I love to serve this side dish with everything from grilled steak, baked beans with ground beef, or roasted pork tenderloin to grilled chicken or brats with quinoa pilaf, roasted potatoes and carrots, or a side salad. The options are nearly endless.
Storage Directions
- Refrigeration: Leftovers can be kept in an airtight container for up to 5 days. They do not freeze well.
- Reheating: Warm the casserole in an oven preheated to 375°F for 10-15 minutes or in the microwave for 1-2 minute intervals until heated.
FAQs
Most often, zucchini does not need to be peeled for baking; as is the case of this recipe for zucchini casserole, the zucchini peel can be left on. This is the same for many sweet zucchini baking recipes as well, but always refer to the recipe you are using for guidance.
If your zucchini casserole is watery, the zucchini expressed moisture as they cooked, and the sauce loosened. You can prevent this from happening by sprinkling the zucchini with salt, tossing it with flour, or pressing it with paper towels. To keep this zucchini casserole easy, I always toss the veggies with flour as it is much quicker and less hassle than salt or paper towels.
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Tools Needed to Make This Recipe
- Cutting Board
- Knife
- Food Processor or Mandoline
- Measuring Cups & Spoons
- 8x8-inch Baking Dish
- Silicone Spatula
- 2-Quart Saucepan
More Savory Zucchini Recipes
- Zucchini Lasagna
- Zucchini Fritters
- Air Fryer Zucchini
- Sautéed Zucchini and Yellow Squash
- Moroccan Roasted Vegetable Salad
- Air Fryer Vegetables
Recipe Card
Cheesy Zucchini Casserole
Ingredients
Casserole
- 3 medium zucchini or 4 small cut into ¼-inch rounds
- 3 tablespoons all-purpose flour divided
- 3 green onions green and white parts thinly sliced
- 2 tablespoons unsalted butter
- 2 minced garlic cloves
- 1 ½ cups milk whole or 2%
- 1 ½ cups shredded sharp white cheddar cheese preferably aged
- ¾ teaspoons salt
- 1 large pinch nutmeg
Panko Topping
- 2 tablespoons unsalted butter melted
- ¾ cup panko breadcrumbs
- 2 tablespoons parmesan cheese
- Fresh cracked pepper optional
Instructions
- Preheat the oven to 375°F. Spray an 8 x 8-inch baking dish with nonstick cooking spray.
- Add the zucchini slices to a mixing bowl. Sprinkle with 4 teaspoons of all-purpose flour and toss until the zucchini is coated evenly with the flour.
- Lay half the floured zucchini slices in the pan, evenly overlapping them. Sprinkle with half of the green onions. Repeat with the remaining zucchini slices and green onions.
- Melt 2 tablespoons of unsalted butter in a saucepan over medium heat until foaming. Add the minced garlic and cook for 1-2 minutes until fragrant and lightly golden.
- Stir in the remaining all-purpose flour, cooking it for 1-2 minutes or until absorbed into the butter, bubbling, and smelling nutty.
- Pour in the milk. Stir or whisk well as it cooks for 3-5 minutes until the mixture has thickened.
- Reduce the heat to low and stir or whisk in the cheddar cheese, salt, and nutmeg until smooth and combined. Remove the saucepan from the heat.
- Pour the cheese sauce over the zucchini and green onions and spread it out evenly so it can seep down around the vegetables.
- Toss the melted unsalted butter, panko breadcrumbs, and parmesan cheese together in a small bowl until combined.
- Sprinkle the breadcrumb mixture over the cheese sauce. Top with freshly cracked pepper if desired.
- Bake in the oven for 30 minutes or until bubbly and the breadcrumb topping is golden. Let sit for 5-10 minutes before serving, allowing the sauce to thicken.
Notes
- Refrigeration: Leftovers can be kept in an airtight container for up to 5 days. They do not freeze well.
- Reheating: Warm the casserole in an oven preheated to 375°F for 10-15 minutes or in the microwave for 1-2 minute intervals until heated through.
