Yellow Squash Casserole

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Yellow Squash Casserole is such an amazing summertime treat.  The dish is cheesy and creamy and bursting with yellow squash flavor.

And the dish is so easy to prepare and is on the table from start to finish in less than 45 minutes!

This is one dish that even finicky vegetable eaters will devour.

A large black cast iron skillet of yellow squash casserole with a serving spoon inserted in the dish.


Yellow squash casserole is very versatile and can be served in a variety of serving vessels.

The dish is best when served hot, but it’s so good, it’s even delicious at room temperature.

Watch us show you how fast and easy it is to make this amazing casserole!



Slicing the squash in a uniform fashion is always best. We like to slice the squash to about 1/4-inch thickness. But you could go thinner, if you desire.

Ensuring the sliced vegetables are identical in thickness will allow them to all cook evenly. You don’t want some of the squash slices to be overly soft, and some to be tough.

TIP: A sharp knife and a steady hand and eye works just fine, but a mandolin is even better.

A hand slicing a yellow squash on a mandolin over a cutting board.

Cook the squash and onion in a large skillet with a little oil until the vegetables just begin to soften, about 10 minutes.

Be sure not to cook the squash too long or it will be come “mushy” in the final dish.

Yellow squash and chopped onion cooking in a large black cast iron skillet.

Grab a large bowl, and mix together all the remaining ingredients, except the Ritz crackers.  You’ll need:

  • 8 oz. sour cream
  • 1/4 cup mayonnaise (want to make it yourself? Click the link! It’s easier than you might think)
  • Salt (we like to use Kosher for a little more texture)
  • 1 & 1/2 cups good quality shredded sharp cheddar cheese
  • 1/2 cup grated Parmesan
  • 1 large egg

After these ingredients are mixed together, gently fold in the cooked squash and onion mixture.

A large glass bowl with a cooked yellow squash, cheese and cream mixture for yellow squash casserole.


If you’re going to have a luscious, cheesy and somewhat gooey filling, you are going to want to topping with a bit of a crunch (and a little extra butter).

The traditional Southern U.S. version of this recipe always uses crushed Ritz crackers as a topping. Who are we to change something that isn’t broken? We do enjoy stirring in some melted unsalted butter, just to increase the flavor as well as bind the crackers together.

We prefer a topping with texture, which is why we don’t completely pulverize the crackers, we like to leave some of the crackers roughly chopped.

TIP: Place the crackers in a large freezer bag and then crush them with the bottom of a measuring cup, or bottle, or even you hands. Don’t over crush them!

Fingers sprinkling crushed Ritz crackers over the casserole in a large black cast iron skillet.

We love serving this casserole in our large 12-inch cast iron skillet, but any 2-quart casserole dish will work. A 9″ x 9″ dish is ideal.

TIP: The casserole can be assembled up to a day in advance, refrigerated, and then baked for an extra 10 minutes (35 minutes total), before serving.


If you’re looking for a lighter, healthier version of a baked squash casserole, be sure to try our Yellow Squash and Tomato Casserole.

This Best-Ever Yellow Squash Casserole is always a crowd-pleasing dish. We find we seldom have left-overs, and be prepared for lots of request for the recipe!

A spoon lifting up a large helping of cooked yellow squash casserole out of the skillet.


That’s easy to answer…YES! The yellow squash has a bit of sweeter taste, which balances beautifully against the sour cream and cheese, but zucchini is good, also.

You can certainly use a combination zucchini and yellow squash, too.

Either way, you will love the taste and texture of this delicious summertime casserole.

An overhead view of a cooked yellow squash casserole with two plates of food nearby.

Ready to make one of the best summertime recipes of all time? AWESOME!

Be sure to take a photo of the finished dish and tag #howtofeedalon and @howtofeedaloon on Instagram!

An overhead view of yellow squash casserole in a large black cast iron skillet.

Best-Ever Yellow Squash Casserole

Yellow Squash Casserol is a Southern U.S. staple side dish and is cheesy, creamy and loaded with summer squash taste. And what's even better, the dish is on the table from start to finish in less than 45 minutes!
4.89 from 9 votes
Print Pin Rate
Course: Side Dish
Cuisine: American, Southern, U.S.
Keyword: Baked squash, Summer Side Dish, Summer squash casserole
Prep Time: 15 minutes
Cook Time: 20 minutes
Total Time: 35 minutes
Servings: 12 people
Calories: 328kcal


  • Mandolin, or sharp knife


  • 1 tbsp vegetable oil
  • 2 & 1/2 lbs yellow squashed sliced
  • 1 cup onion chopped
  • 8 oz. sour cream
  • 1/4 cup mayonnaise
  • 1 tsp Kosher salt
  • 1/2 tsp freshly ground black pepper
  • 1 1&2 cups cheddar cheese shredded
  • 1/2 cup Parmesan cheese grated
  • 1 large egg
  • 1 sleeve Ritz crackers crushed, but not completely pulverised
  • 2 tbsp unsalted butter melted


  • Pre-heat oven to 350°F. Lightly spray a 12-inch cast iron skillet or a 9"x9" casserole dish with cooking spray.
  • In a large skillet, heat the oil over medium-high heat. Add the sliced squash and onion and cook, stirring occassionally, until the vegetables have softened, about 10 minutes. Remove from heat and transfer to a colandar in the sink to drain.
  • In a large mixing bowl, stir together the sour cream, mayonnaise, salt, pepper, cheddar cheese, Parmesan cheese, and egg. Carfeully fold in the cooked squash mixture. Transfer to the prepared baking vessel.
  • In a separate medium bowl, use a fork to stir together the crushed crackers with the melted butter. Sprinkle the mixture all over the top of the casserole.
  • Bake for 25 minutes, uncovered, until bubbly and topping is starting to brown slightly. Remove and serve at once.



Be sure to slice the squash in uniform cuts.  1/4-inch slices are a good thickness.  A mandolin ensures even slicing, but a sharp knife and a steady hand will work just fine.
Don't over sauté the squash and onion.  Cook until just soft.  The vegetables will cook more once the casserole is in the oven.
The casserole can be assembled up to a day in advance and stored in the refrigerator.  Allow to come to room temperature before baking (about 1 hour on the counter), or add an additional 10 minutes to the bake time if no time for bringing to room temperature (total bake time will be 35 minutes).
This casserole is best served hot!


Calories: 328kcal | Carbohydrates: 4g | Protein: 33g | Fat: 52g | Saturated Fat: 32g | Cholesterol: 91mg | Sodium: 846mg | Potassium: 176mg | Fiber: 1g | Sugar: 2g | Vitamin A: 1462IU | Vitamin C: 1mg | Calcium: 958mg | Iron: 1mg
Tried this recipe? Take a Picture!Mention @HowToFeedALoon or tag #HowToFeedALoon!


  • Very good. As stated, a classic Southern recipe. I added red pepper flakes. The only thing left out was a common comment that the mayo should “preferably be Dukes or Hellmans.”

  • 5 stars
    Omg so glad I found this! I made it for holiday dinner tonight and we loved it! My friend needed a side dish for her dinner and I told to make this with me- she just reported it was a hit with her whole crowd. So easy. So good- I did add sea salt and pepper to the squash/onions in the skillet, as well. Officially adding to all holiday side dish menus. Thank you!

    • Hi Caryn! Yay!!! We are thrilled you and your friend had such great success with the squash casserole! That is one of our all-time favorites! Thank you so so much for sharing and for the GREAT review. That means the world to us! Stay in touch! Kris & Wesley

  • 4 stars
    Love anything yellow squash but have a gluten allergy so ritz crackers were not an option. I used 1 1/2 cups pecan crackers made with rice flour and added a 1/4 cup gluten free panko crumbs. Turned out well but like a lot of gluten free dishes didn’t reheat well. Hope you might try to offer some gluten free alternatives in your recipes. Thanks

    • Hi Pam! Of course! We will add more GF dishes to our list of recipes to share! We are glad you enjoyed the squash casserole. And thanks for letting us know!! All the very best, Kris & Wesley

  • Looks yummy but I have a ton of tomatoes to get through too! I saw Squash Tomato Casserole mentioned but cant fine the recipe on your site.

  • Hello Kris,
    I am super excited to try this recipe! I would also love to learn more about your mom’s and grandma’s squash recipe with tomatoes.

    • Hi Ashby! Let us grab that recipe, and I’ll let you know. It’s pretty similar to this recipe, but I’ll dig it up. Thanks and let us know if you make the dish and what you think! All the best, Kris & Wesley

  • 5 stars
    So good! I only cook in cast iron or glass! This was so good. I have to be gluten free so I used toasted gluten free Udi’s bread crumbs. But if you can use the crackers. That is what I use to use. Squash has an unbelievable good taste especially cooked in case iron so you do not cook out the flavor. Thank you so much for this recipe!

    • Hi Terrie!! Yay!!! Cast-iron is the way to go! We are so glad you enjoyed the squash recipe and thank you SO MUCH for letting us know and for the GREAT review. That means the world to us!! xoxoxo Kris & Wesley

  • 5 stars
    I made this for my father for Father’s Day. Everyone said it was “the best ever.” And it TRULY was! Thank you for sharing the recipe with all of us. I have zero natural cooking talent, and my other half was even surprised at how good it was. (Well written and well taught, guys, thanks!) …. I am from South Carolina, and have had every squash casserole ever invented. Yours is definitely the best! Good luck with your two pups. They will keep you busy!!

    • Hi Cassie!! We are so glad you tried our yellow squash casserole and over-the-moon happy that you loved it so much!! It really is such an amazing summertime dish! We are so glad you had such success with it and hope you had wonderful Father’s Day. Thanks so much for letting us know and for the AMAZING review. That means the absolute world to us!!! Stay in touch!! All the best, Kris & Wesley

    • 5 stars
      Made this today. I used one of our zucchini that was out of control in the garden (3 lbs). Sub the onion with a leeks, and added a lb of ground beef.
      Our zucchini will grow out of control again to be sure, and this will be our yummy remedy.

      Thanks for the recipe.

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