Yellow Squash Casserole

Yellow Squash Casserole

If you're from the South—and especially if you have a vegetable garden—summer isn't complete without plenty of servings of buttery, cheesy yellow squash casserole with crispy breadcrumb topping. But really, summer squash casserole is a favorite all year round, and it's as welcome on a holiday table as it is for family meals and potlucks.

Of course you don't have to be from the South to love yellow squash casserole, especially one that's as easy to make as our classic version. And good news if you're entertaining: the recipe is easily scaled up for a potluck dish or large family dinner—simply double all of the ingredients and bake in a larger dish.

The Best Squash for Casserole

You can use straight-neck or crookneck yellow squash for this casserole, or swap in zucchini or any other type of summer squash. You can also make it with two or more types of squash for a colorful casserole!

Look for squash that is firm and free of bruises or soft spots. The best squash should feel heavy for its size. You can also freeze summer squash to use for future casseroles.

Do You Need to Peel Yellow Squash or Remove the Seeds?

Like zucchini, yellow squash has a thin peel and becomes very tender when cooked, so there's no need to peel it. You don't need to remove the seeds from yellow squash either, nor do you need to salt it before cooking. Simply wash the squash well before cooking—it's that easy!

Tips for the Best Yellow Squash Casserole

  • Drain the squash well: Before assembling the casserole, you’ll briefly simmer the squash in salted water and then drain. Be sure to drain it very well so your casserole won’t be watery.
  • Mind the salt: This recipe calls for seasoning the squash with kosher salt, a favorite of many chefs and home cooks. It’s totally fine to use regular table salt, but cut the amount of salt in half if you do so.
  • Choose your cheese: Freshly grated Cheddar cheese tends to melt slightly better than bagged pre-shredded cheese, but this casserole will still be delicious whichever you choose. This casserole works well with anything from mild to extra sharp Cheddar, so use whatever type of Cheddar you prefer. You can also use a blend of cheeses, such as Cheddar and pepper jack.
  • Make a crunchy topping: The secret to the perfect crunchy topping is adding melted butter to the breadcrumbs before putting them on the casserole.

What to Serve with Summer Squash Casserole

This yellow squash casserole goes well with just about any protein, especially BBQ chicken and pork chops. During the summer, another vegetable like green beans or a fresh green salad will complement the meal. It’s also great as part of a vegetarian supper with other Southern favorites, like black eyed peas and macaroni and cheese. And don’t forget to include it among your Thanksgiving sides.

“This summer squash casserole is a great way to get non-veggie eaters to love their vegetables! It’s really quick to whip up and reminded me of a mac and cheese side dish. This would be perfect with a steak and a green vegetable for a summer dinner.” —Tracy Wilk

A Note From Our Recipe Tester


  • 2 medium yellow summer squash (about 1 pound)

  • 1 teaspoon kosher salt, plus more to taste

  • 1 small yellow onion

  • Freshly ground black pepper, to taste

  • 1 large egg

  • 1 teaspoon sugar

  • 3/4 cup shredded Cheddar cheese, divided

  • 1/2 cup mayonnaise

  • 4 tablespoons melted butter, divided, plus more for the casserole dish

  • 1 cup finely ground fresh breadcrumbs

Steps to Make It

  1. Gather the ingredients. Preheat the oven to 350 F.

    The Spruce Eats / Bahareh Niati

  2. Slice the squash and place it in a medium saucepan (no need to peel or remove the seeds). Cover the squash with water and add 1 teaspoon of kosher salt.

    Place the pan over high heat and bring the squash to a boil. Reduce the heat to medium-low and cover the pan; continue to cook until tender, about 10 to 15 minutes.

    A large pan of sliced squash in boiling, salted water

    The Spruce Eats / Bahareh Niati

  3. Meanwhile, peel and finely dice the onion.

    A cutting board with finely diced onion and a knife

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  4. Drain the squash thoroughly; return it to the saucepan, and mash it. Taste the squash and add salt and pepper, if desired.

    A pan of mashed, cooked squash topped with salt and pepper

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  5. In a bowl, whisk the egg and sugar lightly. Add the mayonnaise, diced onion, 1/2 cup of the cheddar cheese, and 2 tablespoons of the melted butter. Stir to blend thoroughly.

    A bowl of mixed egg and sugar, topped with mayonnaise, diced onion, cheddar cheese, and melted butter

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  6. Stir the mashed squash into the egg and mayonnaise mixture.

    A bowl of mashed yellow squash mixed into the egg-mayonnaise mixture

    The Spruce Eats / Bahareh Niati

  7. Butter a 1-quart casserole or baking dish. Spoon the mixture into the prepared casserole.

    A large baking dish with unbaked mashed squash mixture

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  8. Top the casserole with the remaining 1/4 cup of shredded cheese.

    A baking dish with unbaked mashed yellow squash mixture topped with shredded cheese

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  9. Toss the breadcrumbs with the remaining 2 tablespoons of melted butter and then sprinkle them over the casserole.

    An unbaked yellow squash casserole in a baking dish, topped with breadcrumbs

    The Spruce Eats / Bahareh Niati

  10. Bake until bubbly and lightly browned, about 40 to 45 minutes. Serve squash casserole hot.

    A baked yellow squash casserole in a baking dish

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Recipe Variations

  • Add some colorful veggies: Add chopped red peppers or green peppers with the onion to add color as well as flavor.
  • Spice it up: You can spice this casserole up by adding diced chiles, such as jalapeños, along with the onion. Alternately, you can add a little hot sauce to the squash mixture, or top the casserole with pepper jack cheese.
  • Mix up the topping: Instead of breadcrumbs, try using crushed buttery crackers such as Ritz.


This casserole can be assembled a day ahead and stored in the refrigerator. Add the breadcrumb topping just before baking.

How to Store this Casserole

Leftovers will keep in the refrigerator for up to three days. Reheat in the oven and run under the broiler briefly to re-crisp the topping. You can also freeze the casserole for up to three months in a freezer-safe airtight container. Reheat in the oven until warmed through and briefly broil before serving.


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