This Best-Ever Yellow Squash Casserole features tender, mandolin-sliced squash sautéed with onions and folded into a rich, cheesy sour cream and mayonnaise base. Baked in a cast-iron skillet until bubbly and finished with a signature buttery Ritz cracker topping, it’s the ultimate comfort food for any family gathering.
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🧀 The Ingredients
This recipe brings together fresh garden produce and a rich, creamy base, all finished with a classic savory topping that provides a satisfying crunch in every bite. Find ingredient notes (including substitutions and variations) below.
📝 Ingredient Notes and Substitutions
- Yellow Squash: Using a mandolin ensures uniform slices that cook evenly; you can also substitute half the squash with zucchini for a colorful twist.
- Sour Cream and Mayonnaise: This duo creates a rich, velvety base, but you can swap the sour cream for plain Greek yogurt if you prefer a tangier, slightly lighter profile.
- Cheddar and Parmesan Cheese: Sharp cheddar offers a bold flavor while the Parmesan adds a salty umami kick; feel free to use Monterey Jack or Gruyère for a different melting consistency.
- Ritz Crackers: These provide the signature buttery crunch, though Panko breadcrumbs or crushed saltines can be used as a substitute in a pinch.
- Egg: The egg acts as a vital binder that helps the creamy sauce set during baking, ensuring the casserole holds its shape when served.
- Onion: A yellow or Vidalia onion is recommended for its mellow sweetness, but shallots can be used for a more delicate flavor.
Refer to the recipe card (with video) below for a full list of ingredients and measurements.
🔥 Tips and Tricks for Perfect Squash Casserole
- Drain Excess Moisture: Squash has a high water content; after sautéing, if you notice extra liquid in the pan, drain it before mixing the squash into the creamy base to prevent a soggy casserole.
- Don’t Overcook the Squash: Sauté the squash just until it’s tender-crisp; it will finish softening in the oven, and this prevents the final dish from becoming mushy.
- Mandolin Safety: Always use the hand guard or a cut-resistant glove when slicing your squash to ensure perfectly even slices while protecting your fingers.
- The Skillet Advantage: Using a cast-iron skillet not only provides a beautiful rustic presentation but also retains heat better, keeping the casserole warm throughout the entire meal.
- Perfectly Golden Topping: For the best results, toss the crushed Ritz crackers thoroughly with the melted butter in a small bowl before sprinkling them over the top to ensure an even, golden-brown crunch.
- Let it Rest: Allow the casserole to sit for 5 to 10 minutes after removing it from the oven; this helps the sauce set so you get a perfect scoop every time.
How to Make Yellow Squash Casserole
- Step 1: Use a mandolin or a sharp knife to slice the squash into ¼-inch rounds.
- Step 2: Sauté the sliced squash and onion in the oil over medium heat in a large skillet until soft, about 10 minutes. If there is excess liquid, drain in a colander.
- Step 3: In a large bowl, combine the sour cream, mayonnaise, cheddar cheese, Parmesan cheese, egg, salt, and pepper.
- Step 4: Carefully fold the sautéed squash into the sour cream and cheese mixture. Stir to fully combine. Transfer to a grease pan or baking dish.
- Step 5: Combine the crushed crackers with the melted butter and then sprinkle them over the top of the casserole.
- Step 6: Bake until golden and bubbly, about 25 minutes. Let rest for 5 minutes and then serve.
🍽️ How to Serve
- The Classic Southern Side: Serve this casserole as a traditional side dish alongside roasted chicken, pan-seared pork chops, or a honey-glazed ham.
- Summer BBQ Companion: It pairs perfectly with grilled favorites like BBQ ribs, burgers, or steak, making it a hit at backyard cookouts.
- Holiday Table Staple: Include this dish in your Thanksgiving or Easter spread as a creamy, comforting alternative to standard potato or green bean sides.
- Vegetarian Main Course: For a lighter dinner, serve a large helping of the casserole with a crisp green garden salad and a piece of crusty bread.
- Skillet Presentation: Bring the cast-iron skillet directly to the table for a rustic, “farm-to-table” look that keeps the casserole hot for second helpings.
- Fresh Garnish: Enhance the presentation and add a hint of freshness by sprinkling chopped parsley or chives over the golden cracker topping just before serving.
🙋🏽♂️ Frequently Asked Questions
How do I prevent my Yellow Squash Casserole from becoming too watery?
To avoid a runny consistency, make sure to sauté the vegetables first and drain any excess liquid before mixing them with the creamy base.
Can I prepare this Yellow Squash Casserole in advance?
Yes, you can assemble the vegetable and cheese mixture a day early, store it in the refrigerator, and then add the buttery cracker topping just before placing it in the oven.
Is it possible to freeze Yellow Squash Casserole?
While it is safe to do so, the texture of the vegetables may become softer upon thawing; for the best results, freeze the casserole without the topping and add fresh crumbs when you are ready to bake.
Can I use zucchini instead of squash in this Yellow Squash Casserole?
Absolutely, you can swap in an equal amount of the green variety or use a combination of both for a colorful and delicious variation of the dish.
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Best-Ever Yellow Squash Casserole
Yellow Squash Casserole 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!
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Servings: 12 people
Calories: 328kcal
Video
Equipment
- Mandolin, or sharp knife
Ingredients
- cooking spray
- 1 tablespoon vegetable oil
- 2½ lbs yellow squash sliced into ¼-inch rounds
- 1 cup onion chopped
- 8 oz. sour cream
- ¼ cup mayonnaise
- 1½ cups cheddar cheese shredded
- ½ cup Parmesan cheese grated
- 1 large egg
- 1 teaspoon Kosher salt
- ½ teaspoon freshly ground black pepper
- 1 sleeve Ritz crackers crushed, but not completely pulverised
- 2 tablespoon unsalted butter melted
Instructions
- Pre-heat oven to 350°F. Lightly spray a 12-inch cast-iron skillet or a 9"x9" casserole dish with cooking spraycooking spray
- In a large skillet, heat the oil over medium-high heat. Add the sliced squash and onion and cook, stirring occasionally, until the vegetables have softened, about 10 minutes. If there is excess liquid, transfer to a colander in the sink to drain.1 tablespoon vegetable oil, 2½ lbs yellow squash, 1 cup onion
- In a large mixing bowl, stir together the sour cream, mayonnaise, cheddar cheese, Parmesan cheese, egg, salt, and pepper. Carefully fold in the cooked squash mixture. Transfer to the prepared baking pan or dish.8 oz. sour cream, ¼ cup mayonnaise, 1½ cups cheddar cheese, ½ cup Parmesan cheese, 1 large egg, 1 teaspoon Kosher salt, ½ teaspoon freshly ground black pepper
- 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.1 sleeve Ritz crackers, 2 tablespoon unsalted butter
- Bake for 25 minutes, uncovered, until bubbly and the topping is starting to brown slightly. Remove and serve at once.
Notes
NOTE: Watch the video in the recipe card for visual guidance.
Be sure to slice the squash into uniform cuts. ¼-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 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!
Nutrition
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
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Kevin Carson says
Squash casserole was one of my childhood summer favorites. Also fresh zucchini fritters and zucchini bundt cake were a delicious way of using up too much of a good thing.
Kris Longwell says
Yes to all of this!!! We’ve never done a zucchini bundt cake, but now we must!!! Thanks, Kevin!!
Teresa Reynolds says
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.”
Kris Longwell says
Hi Teresa! Sounds like you prepared it perfectly! And heck yes to Dukes or Hellmans! The best!!
Caryn says
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!
Kris Longwell says
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
Pam Frank says
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
Kris Longwell says
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
JANICE WALSH says
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.
Kris Longwell says
Hi Janice! We don’t actually have a squash tomato casserole (at least we don’t think we do! LOL!), but we do have a tomato pie recipe that is heavenly! So is our Tomato Tart with Corn and Fresh Herbs and our Stuffed Tomatoes are so good, too!! Hope this helps!
Myra says
I make this ,but i ad frozen carrots and use frozen squash.my family loves it.
Kris Longwell says
Hi Myra! Yum!! Carrots sound like a wonderful addition! Thanks for letting us know and for the GREAT review! We appreciate that so so much!! All the best, Kris & Wesley
Olivia says
Question! If I am cooking for two, and only have 1.5 pounds of squash on hand could I cut the recipe in half?
Kris Longwell says
Hi Olivia! Absolutely! Let us know how it turns out!!
Gayle says
She’ll be sorry she won’t have leftovers! So glad I doubled it!
Blanca says
This is my new favorite use for yellow squash!
Kris Longwell says
Hi Blanca!! YES!! We are so happy you enjoyed the yellow squash recipe! We love it so much, too!! Thanks again and please stay in touch! All the best, Kris & Wesley
Ashby says
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.
Kris Longwell says
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
Terrie says
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!
Kris Longwell says
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
Cassie says
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!!
Kris Longwell says
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
Rick says
Could frozen squash be used?
Kris Longwell says
Sure! Fresh would be better, but thawed frozen will still be quite tasty. Hope this helps!
Kat says
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.
Michelle Hammett says
Made this the other night and it is so good. Will continue to make this often.
Kris Longwell says
Awesome!! We make this at least once or twice a month!! So glad you like it, too!!
Rick says
Making this today!