Zucchini Squash Casserole with Crispy Topping

Savor the simple pleasures of Southern cooking with this Zucchini Squash Casserole recipe. Made with fresh ingredients and baked in a cast iron skillet, this dish offers a creamy filling and a satisfyingly crispy topping.

This Squash Casserole is comfort food, through and through. Imagine tender summer squash baked in a rich, creamy sauce, all tucked under a bubbling, golden-brown crust of cheesy, buttery breadcrumbs. It’s the kind of dish I’m always happy to share at family dinners, potlucks, and holiday suppers, bringing a taste of Southern hospitality to the table.

Overhead view of a cast iron skillet filled with a baked zucchini and yellow squash casserole, topped with golden, crispy breadcrumbs and cheese. A serving spoon scoops up a portion, revealing tender, layered vegetables.
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5-Star Reader Comment

“Wow! This is so yummy! I was specifically looking for a smaller “casserole” for 2 people. This is going in the rotation for sure. Thanks so much. I’m looking at your other recipes to try out.”

Lori

The Secret Weapon: Why Cast Iron is Fantastic for Casseroles

While you can use a standard casserole dish, learning how to use a cast-iron skillet is easy and truly elevates this recipe. Here’s why it’s my secret weapon:

  • Superior Heat: Cast iron heats evenly and retains that heat exceptionally well. This means your casserole cooks uniformly from the center to the edges, ensuring a perfectly set, creamy sauce throughout.
  • An Unbeatable Crust: The direct, intense heat from the iron sears the bottom and sides of the casserole, creating a delicious, golden-brown crust that’s impossible to achieve in a glass or ceramic baking dish.
  • Stovetop to Oven to Table: A cast iron skillet is the ultimate multitasker. You can transition from sautéing aromatics on the stovetop (if you choose to add them) to baking in the oven without needing to dirty another pan.

Ingredients You’ll Need

Overhead view of labeled ingredients for zucchini and squash casserole on a marble surface, including sliced yellow squash and zucchini, butter, panko breadcrumbs, mayonnaise, milk, olive oil, garlic powder, kosher salt, black pepper, and fresh parsley.
  • Grab butter, mayonnaise, milk, salt, pepper, and garlic powder for the sauce.
  • Fresh Squash is a must, and I like to use a combination of green and yellow summer squash and zucchini sliced into rounds.
  • To make the topping, you need panko breadcrumbs, butter, olive oil, and parmesan cheese.

Beyond The Basics: Variations You’ll Love

  • Buttery Crackers: Instead of Panko, use about a cup of crushed buttery crackers like Ritz or Townhouse.
  • Cheddar Cheese: For a more traditional Southern squash casserole, substitute the Parmesan with an equal amount of sharp cheddar cheese, or use a mix of both.
  • Add Onions: For extra flavor, sauté a chopped sweet Vidalia onion (my fav) in the skillet until soft before adding the squash.
  • More Veggies: Sauteed vegetables, such as garlic, bell peppers, or mushrooms, are delicious add-ins.

Instructions For Southern Squash Casserole

Four-step collage showing how to make zucchini and yellow squash casserole in a cast iron skillet. Step 1: Melting butter. Step 2: Arranging sliced squash and zucchini in a spiral pattern. Step 3: Topping with cheese and breadcrumbs. Step 4: Fully baked casserole with a golden, crispy topping.
  1. Preheat the cast iron skillet in the oven. Then add butter to the pan and let it melt (while in the oven).
  2. Carefully arrange the sliced vegetables in the buttered skillet. Stir together the mayonnaise and milk and pour over the squash. Sprinkle on salt, pepper, garlic powder, and add Parmesan cheese. Cover the skillet with tin foil and place it in the oven.
  3. Melt butter, add olive oil and Panko bread crumbs, and mix. Remove the skillet from the oven, then sprinkle on buttered Panko crumbs and the remaining cheese. Place back in the oven, and bake for 10 minutes until the topping is golden brown.
  4. Let cool for 5 minutes then serve.

Frequently Asked Questions

Can I make this squash casserole ahead of time?

Yes! To make it ahead, assemble the entire casserole in the skillet but do not add the breadcrumb topping. Cover and refrigerate for up to 24 hours. When you’re ready to bake, prepare the topping, sprinkle it over the casserole, and bake as directed, adding 5-10 minutes to the initial covered baking time.

Can I make it without a cast iron skillet?

Yes, you can make this casserole recipe without a skillet! If you don’t have a cast iron at home, you can use any heavy-bottom metal pan or other large skillet. If available, you can also use a 9×9 baking dish or a pie dish.

Can I use frozen squash for this recipe?

You can, but it requires an extra step. Thaw the frozen squash completely and then press it between paper towels or in a colander to remove as much excess water as possible. Sautéing the thawed squash before assembling is highly recommended to prevent a watery result.

Do I need to peel yellow squash and zucchini?

No, you don’t! The skin is thin and tender, so there’s no need to peel it. Just give it a good wash and you’re ready to go.

Plate of baked zucchini and yellow squash casserole topped with golden, crispy breadcrumbs and shredded cheese, served with a fork on a ceramic plate.

Storing, Freezing, and Reheating Instructions

To Store: Leftovers can be stored in an airtight container in the refrigerator for up to 4 days.

To Freeze: Follow the “make-ahead” freezing instructions above for best results.

To Reheat: For the crispiest topping, reheat individual portions in an oven or air fryer at 350°F until warmed through. Microwaving will work, but the topping will lose its crunch.

How To Serve Squash Casserole

This casserole recipe makes one delicious dinner served with Crock Pot Chicken Thighs or Pork Tenderloin! Pair it with other Southern classics, like One Pot Mushroom Rice and this Creamy Cucumber Salad.

More Squash Recipes You’ll Love

If you tried this Zucchini Squash Casserole Recipe or any other recipe, please leave a star rating and let me know how it went in the comments below. Thanks!

Zucchini Squash Casserole with Crispy Topping

5 from 3 reviews
Prep Time: 10 minutes
Cook Time: 30 minutes
Total Time: 40 minutes
Servings: 4
Calories: 305kcal
Print Pin Rate
Squash Casserole is a classic Southern side dish that's pure perfection! Beautiful yellow squash is layered into a cast iron, topped with a crunchy, cheesy crust, and then drizzled with a light butter sauce to create an irresistibly flavorful dish everyone will love.

Ingredients

  • 2 tablespoons butter
  • 4 – 5 cups squash – sliced
  • ¼ cup mayonnaise
  • 2 tablespoons milk
  • 1 teaspoon salt
  • ½ teaspoon pepper
  • ¼ teaspoon garlic powder
  • cup Panko breadcrumbs
  • 1 tablespoon butter
  • 1 tablespoon olive oil
  • 3 tablespoons Parmesan cheese

Instructions

  • Heat oven to 375 degrees. Place the cast iron skillet in the oven to heat. When it's come up to temp, take the skillet out of the oven and place 2 tablespoons of butter into the pan. Place the skillet back into the oven for 3 minutes or until butter melts.
  • Carefully place sliced squash in a buttered skillet. In a small bowl or cup, mix together mayonnaise and milk. Pour over squash. Sprinkle on salt, pepper, garlic powder, and 1 tablespoon of Parmesan cheese. Cover the skillet with tin foil and place in the oven. Cook for 20 minutes.
  • Melt butter in an oven proof dish. Add olive oil and Panko bread crumbs and mix. Set aside. Take the skillet out of the oven and remove foil. Sprinkle on buttered Panko crumbs and remaining Parmesan cheese. Place skillet back in oven, uncovered, and cook an additional 10 minutes until topping is golden brown.
  • Remove skillet from oven and let cool for 5 minutes before serving.

Notes

Recipe Variations:
  • Buttery Topping: Enhance the buttery flavor with crushed Ritz or Townhouse crackers.
  • Sharp Cheese: Create a more pronounced Southern flavor with sharp cheddar.
  • Sweet Onion: Add a touch of sweetness by sautéing a Vidalia onion.
  • Veggie Boost: Add sautéed garlic, bell peppers, or mushrooms for an extra layer of flavor.
Storing and Reheating:
  • Storing: Keep leftovers fresh for up to 4 days in an airtight container in the fridge.
  • Freezing: For best quality after thawing, follow make-ahead freezing directions.
  • Reheating: Reheat in oven/air fryer (350°F) to restore topping’s crispness. Microwave if needed, but expect a softer topping.
Make Ahead: Assemble casserole (without topping) in skillet. Cover and refrigerate up to 24 hours. Top and bake as directed, adding 5-10 minutes to covered bake time.

Nutrition

Serving: 1serving · Calories: 305kcal · Carbohydrates: 21g · Protein: 4g · Fat: 24g · Saturated Fat: 8g · Polyunsaturated Fat: 7g · Monounsaturated Fat: 8g · Trans Fat: 0.4g · Cholesterol: 32mg · Sodium: 843mg · Potassium: 528mg · Fiber: 3g · Sugar: 4g · Vitamin A: 15196IU · Vitamin C: 29mg · Calcium: 135mg · Iron: 1mg

Top Tips for a Perfect, Non-Watery Casserole

  • For the Creamiest Sauce, Shred Your Own Cheese: While pre-shredded cheese is convenient, it’s often coated with anti-caking agents like cellulose. These agents can prevent the cheese from melting into the smooth, velvety sauce this casserole deserves. For the best results, buy a block of Parmesan or cheddar and shred it yourself.
  • Protect the Topping for Maximum Crunch: If you notice your cracker or breadcrumb topping is browning too quickly before the casserole is heated through, simply lay a piece of aluminum foil loosely over the top of the skillet for the remainder of the baking time. This shields the topping from the direct heat, preventing it from burning while the filling gets hot and bubbly.
Yellow squash cooked in a cast iron skillet is a new take on a southern favorite dish. Lightened up a bit with all the flavors you love. Topped with a cheesy, buttery crust for a simple, delicious side dish.
Squash casserole in cast iron skillet with cheese.

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21 Comments

  1. 5 stars
    We loved this recipe! It turned out pretty and delicious. While the pan was heating in the oven, I made little squash towers alternating the green and yellow. You have to be careful putting them in the super hot pan, for sure! A couple “towers” collapsed on the way from the cutting board to the pan and had to be rebuilt. lol Will maybe pop under the boiler a bit next time. I’m going to add sautéed mushrooms next time, what a great idea. It’s a keeper, thanks!

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