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Yellow Squash Casserole

This easy recipe for Yellow Squash Casserole is the perfect way to enjoy garden-fresh yellow squash in a creamy comforting side dish. Make it during the summer months or whip it up for the holiday season for everyone to enjoy! 

While there are many ways to prepare and cook yellow squash, turning it into a comforting casserole is hands down the best way. Who wouldn’t love fork-tender squash baked in with a creamy sauce? And that’s not even the best part!

This creamy yellow squash casserole is topped with a decadent topping made with buttery crackers and cheese mixed with butter. When baked in the oven, it produces a crunchy topping that completely transforms this dish into a comfort food you’ll want to make over and over again. 

While yellow squash is in season in the summer, this recipe is also a hit for the holiday months and pairs well with Oven Roasted Turkey and Classic Garlic Mashed Potatoes

Squash Casserole on a white plate.

How To Make Yellow Squash Casserole:

  1. Preheat the oven to 350°F. Add olive oil to a large skillet and turn to medium-low heat. Gently cook the squash and onions until they become soft and release their flavor. Remove from heat. 
  2. In a bowl, add mayonnaise, egg, cheddar cheese, Parmesan cheese, flour, garlic powder, salt, and pepper in a large bowl. Add the squash and onions, and stir to coat, then transfer to a casserole or baking dish. 
  3. In a bowl, add combine the crushed crackers, Parmesan cheese, and melted butter and stir to combine. Evenly distribute the cracker topping on top of the casserole.
  4. Add the yellow squash casserole to the oven and bake for 30 minutes or until the topping is golden brown and the squash is fork-tender. Let it sit for 10-15 minutes to set before serving hot.
Collage showing how to make yellow squash casserole.

Yellow Squash Casserole Recipe Tips

  • While it may seem easier to just bake the raw vegetables, they must be sauteed first to release any excess moisture. Make sure to drain any excess liquid from the cooked squash before adding it to the mayonnaise mixture. Otherwise, the filling will be soupy.
  • If you don’t like mayonnaise, you can mix it with sour cream or just use sour cream and completely omit the mayonnaise. 
  • While the egg does help bind the casserole together, you can omit it with little difference in texture. 
  • Splurge on a good cut of cheese for this dish as an inexpensive cheese can lead to a grainy, oily casserole after it bakes.
  • If you have trouble getting even slices on the yellow squash, use a mandolin!


  • Give this casserole a kick of heat by adding some freshly diced jalapenos or canned green chilies. 
  • If you have extra Saltines or oyster crackers on hand, feel free to use them instead of buttery crackers. Bread crumbs or ground-up potato chips will work well too!
  • Mix up the cheeses by using pepper jack, pecorino romano, or your favorite salty cheese. 
  • Slice up the yellow squash into rounds instead of dicing it into cubes for a change in shape and texture. 
Yellow squash casserole on a white serving plate.

Storing and Freezing

Storing: This casserole can be stored in an airtight container in the fridge for 4-5 days. You can keep it in the casserole dish by tightly wrapping it with plastic wrap.

Freezing: Because yellow squash is a delicate vegetable, it does not hold up well when frozen then thawed. Therefore, freezing is not recommended.

Yellow squash casserole served on a white plate.

Yellow Squash Casserole

4.6 from 20 votes
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Prep Time: 15 minutes
Cook Time: 35 minutes
Time to Cool: 15 minutes
Total Time: 1 hour 5 minutes


Squash Casserole Filling

  • 1 tablespoon olive oil
  • 2 large yellow squash cut into 1-inch pieces (about 4 to 5 cups)
  • 1 cup sweet white onions diced
  • 1 cup mayonnaise
  • 1 large egg
  • 1 cup cheddar cheese shredded off the block
  • ½ cup Parmesan cheese shredded off the block
  • 1 tablespoon all-purpose flour
  • 1 teaspoon garlic powder
  • Salt and pepper to taste

Cracker Topping

  • ½ cup finely crushed butter crackers similar to Ritz crackers, about ½ sleeve
  • ¼ cup Parmesan cheese finely shredded off the block
  • 2 tablespoons unsalted butter melted


Squash Casserole Filling:

  • Preheat the oven to 350ºF, and lightly grease a 2-quart baking dish.
  • In a large skillet, heat the olive oil over low-medium heat. Add the squash and onions, and cook until they begin to soften slightly (about 4 to 5 minutes). Remove from heat.
  • Combine the mayonnaise, egg, cheddar cheese, Parmesan cheese, flour, garlic powder, salt, and pepper in a large bowl. Add the squash and onions, and stir to coat. 
  • Transfer the squash mixture to the prepared baking dish.

Cracker Topping:

  • In a separate small bowl, combine the crushed crackers, Parmesan cheese, and melted butter.
  • Top the squash mixture with the cracker mixture, and spread into an even layer. 
  • Place the casserole into the oven, and bake for 30 minutes or until the top is golden brown and the filling is bubbly.
  • Remove from the oven, and allow the casserole to cool for 10 to 15 minutes before serving.
  • Store leftovers in the refrigerator for up to 3 days.


*The calories listed are an approximation based on the ingredients in the recipe card and a serving size of ½ cup of casserole. Actual calories will vary.
*For more information, tips, and answers to frequently asked questions, please refer to the post.


Serving: 1/2 cup | Calories: 256kcal | Carbohydrates: 8g | Protein: 6g | Fat: 23g | Saturated Fat: 7g | Polyunsaturated Fat: 15g | Cholesterol: 42mg | Sodium: 331mg | Fiber: 1g | Sugar: 3g
Recipe Rating


Friday 27th of August 2021

Can you make the squash mixture the day before and keep in the refrigerator over night and then place in casserole and topping the next day to bake?


Friday 27th of August 2021

Hi Ed!

We haven't tried to prep the filling ahead of time. I'm not sure how it would work, but I'd be concerned about the squash releasing additional liquid and making the filling soupy. If you decide to try it, we'd love to know how it turns out. Have a lovely weekend! :)