The Ultimate Easy Yellow Squash Casserole with Buttery Ritz Cracker Topping

There’s nothing quite like a classic squash casserole to bring comfort and deliciousness to any meal. This beloved dish features tender yellow squash, creamy sour cream, a rich blend of melted cheddar and parmesan cheeses, and is crowned with a irresistibly buttery Ritz cracker topping. It’s a simple yet incredibly satisfying recipe that’s perfect for both casual family dinners and festive holiday gatherings, embodying the best of homemade comfort food.

Close up photo of Squash Casserole with a serving removed, showcasing the creamy interior and golden-brown cracker topping

Why This Yellow Squash Casserole Recipe Shines

This yellow squash casserole isn’t just a side dish; it’s a culinary star that truly stands out. Its appeal lies in its perfect balance of textures and flavors – from the soft, perfectly cooked squash to the rich, cheesy, and savory base, all complemented by that crunchy, golden-brown Ritz cracker crust. Here’s why this recipe deserves a spot in your rotation:

Effortlessly Delicious: Despite its gourmet taste, this casserole is remarkably easy to prepare. With straightforward steps and common ingredients, even novice cooks can achieve a show-stopping result.
Versatile for Any Occasion: Whether you’re planning a cozy weeknight meal, a bustling holiday feast, or a vibrant summer barbecue, this squash casserole fits right in. It’s hearty enough for cooler months and light enough for warmer weather.
Quick to Assemble: Forget recipes that demand hours in the kitchen. This squash casserole comes together in under 30 minutes of active prep time, making it ideal for busy schedules.
Unforgettable Flavor Profile: The combination of mild yellow squash with tangy sour cream, sharp cheddar, savory Parmesan, and the buttery, slightly salty Ritz crackers creates a symphony of flavors that will have everyone asking for seconds.

Squash, in general, is often underestimated, but it truly shines in dishes like this. From zucchini casserole to baked spaghetti squash and even air fryer acorn squash slices, these savory sides deserve more recognition, and this delightful casserole is certainly no exception!

Squash Casserole on a plate with a fork, ready to be enjoyed

Key Ingredients You’ll Need

Crafting this incredible yellow squash casserole requires a handful of fresh, high-quality ingredients. While the full, printable recipe with exact measurements is provided at the end of this post, here’s a detailed look at what you’ll need and some helpful tips for each.

All the fresh and dairy ingredients neatly laid out for Squash Casserole preparation

Ingredient Info and Substitution Suggestions

Each component plays a crucial role in the casserole’s final texture and taste. Here’s how to choose and, if necessary, substitute them:

Yellow Squash: For this recipe, we recommend using six medium-sized yellow squash, sliced into 1/4-inch thick rounds. When selecting squash, look for ones that are firm to the touch, feel heavy for their size, and have smooth, shiny skin. Avoid any with soft spots or blemishes. You don’t need to peel them; the skin helps the rounds hold their shape during baking.
Onion: A medium to large yellow onion, finely chopped, adds a foundational savory note. It cooks down with the squash, infusing the dish with subtle sweetness. White or sweet onions can also be used.
Cheese Blend: We prefer sharp cheddar cheese because its robust flavor truly stands out in the creamy base. However, feel free to use mild or extra-sharp cheddar based on your preference. For the topping, grated Parmesan cheese adds a salty, umami depth. Don’t hesitate to experiment with your favorite cheese blend, perhaps adding a touch of Monterey Jack or Gruyere for different nuances.
Sour Cream: Full-fat sour cream is key to achieving that rich, creamy texture. It contributes a slight tang that balances the richness of the cheese. If you’re looking for an alternative, Greek yogurt (full-fat) can be used for a similar tang and creaminess, though it might make the casserole slightly thinner.
Eggs: Eggs act as a binder, helping the casserole set and hold its shape. Two large eggs are sufficient to emulsify the creamy mixture and ensure a cohesive dish.
Seasonings: Simple yet effective, sea salt, fresh thyme, and ground black pepper elevate the natural flavors of the squash and cheese. Fresh thyme is highly recommended for its aromatic qualities, but dried thyme can be used in a smaller quantity (about 1/4 teaspoon). Adjust salt and pepper to your taste.
Ritz Cracker Topping: The iconic buttery Ritz cracker topping is what truly ties this casserole together, offering a delightful crunch and a hint of saltiness. If Ritz crackers aren’t available or preferred, you can substitute them with regular breadcrumbs (panko for extra crispiness) or crushed saltine crackers. Just ensure they are mixed well with melted unsalted butter.
Water: A small amount of water is used to gently steam the squash and onion until tender, ensuring they are perfectly cooked before mixing into the creamy base.

Step-by-Step: How to Make Squash Casserole

These step-by-step photos and instructions are here to help you visualize how to make this recipe. For a complete, printable version of this recipe with all measurements and detailed instructions, please Jump to Recipe at the bottom of this post.

Prepare Your Baking Dish: Begin by preheating your oven to 400°F (200°C). Lightly grease a 9×9 inch square glass baking dish. This will prevent the casserole from sticking and ensure easy serving.
Cook the Squash and Onion: In a large skillet or pan, combine your sliced yellow squash and chopped yellow onion with 1/3 cup of water. Cook over medium-high heat for approximately 8-10 minutes, or until the vegetables are tender but not mushy. It’s crucial not to overcook them, as they will continue to bake in the oven. Once cooked, transfer the squash and onion to a strainer to drain any excess water.
Expert Tip: Squash has a high water content. To prevent a watery casserole, allow the cooked squash and onion to sit in the strainer for several minutes. You can gently press down on them with the back of a spoon to encourage more water to release, but be careful not to mash them. This step is vital for achieving the perfect consistency.
Combine the Creamy Filling: While the squash drains, in a separate medium-sized mixing bowl, whisk together the shredded sharp cheddar cheese, full-fat sour cream, eggs, sea salt, fresh thyme, and ground black pepper until well combined. Once the squash and onion have cooled slightly and are well-drained, add them to this creamy mixture. Gently fold everything together until the vegetables are evenly coated. If the mixture appears too liquidy, you can carefully drain a bit more liquid before transferring.
Assemble and Top with Parmesan: Pour the squash and creamy filling mixture into your prepared baking dish, spreading it evenly. Then, sprinkle a generous 1/4 cup of grated Parmesan cheese over the top of the mixture. This layer of Parmesan will add another dimension of cheesy flavor as it bakes.
Add the Ritz Cracker Topping and Bake: In a small bowl, combine the crushed Ritz crackers with the melted unsalted butter. Mix thoroughly until the crackers are evenly coated with butter. Sprinkle this buttery cracker mixture in an even layer over the Parmesan cheese on the casserole. Bake for approximately 15 minutes, or until the topping is golden brown and the casserole is bubbling around the edges.
Garnish and Serve: Once baked to perfection, remove the casserole from the oven. For an extra touch of freshness and aroma, garnish with a little more fresh thyme before serving. Allow it to cool for a few minutes before diving in, as this helps the casserole set slightly. Enjoy this comforting dish warm!

Frequently Asked Questions & Expert Tips for the Perfect Casserole

Why is my squash casserole watery?

Squash naturally has a very high water content, which can easily lead to a watery casserole if not properly managed. The most common culprit is not draining the cooked squash and onion thoroughly enough before mixing them with the other ingredients. Make sure to let the squash sit in a strainer for a few minutes, gently pressing it down to release as much excess liquid as possible without mashing it. Also, avoid overcooking the squash in the skillet; they should be tender but still have a slight firmness, as they will continue to cook and release more moisture in the oven. Overcooked squash can also become mushy and contribute to a watery texture.

Can I add zucchini to this recipe?

Absolutely! Zucchini is a fantastic addition and pairs wonderfully with yellow squash. You can use a combination of both zucchini and yellow squash if desired, maintaining the same total amount of vegetables. Just like yellow squash, ensure the zucchini is sliced to a similar thickness and thoroughly drained after cooking to prevent excess moisture. If you’re specifically looking for a zucchini-based dish, we have a fantastic zucchini casserole recipe you might enjoy.

Do you need to peel the squash for this casserole?

No, there’s no need to peel the yellow squash for this recipe. The skin is thin, tenderizes nicely during cooking, and is perfectly edible. In fact, leaving the skin on helps the squash rounds maintain their shape better after being baked, contributing to a more appealing presentation and texture in the finished casserole.

Can you make squash casserole ahead of time?

Yes, this casserole is an excellent make-ahead option! You can prepare the entire casserole mixture (squash, onion, cheese, sour cream, eggs, seasonings) a day in advance. Store it, covered, in the refrigerator. When you’re ready to bake, allow the casserole to sit at room temperature for about 30 minutes while your oven preheats (this is especially important if you’re using a glass baking dish to prevent thermal shock). Add the buttery Ritz cracker topping just before baking to ensure it bakes up perfectly crispy. You might need to add a few extra minutes to the baking time if the casserole is going into the oven cold.

How do you store leftovers and reheat them?

To store leftovers, allow the casserole to cool completely to room temperature. Then, transfer any remaining portions to an airtight container and store them in the refrigerator for up to 4 days. For reheating, the best method is to use a 350°F (175°C) oven until it’s warmed through, usually about 15-20 minutes. This helps maintain the texture of the topping. You can also microwave individual servings, but the topping may lose some of its crispness.

Can I freeze squash casserole?

While you can freeze cooked squash casserole, the texture of the squash and dairy components might change slightly upon thawing and reheating, becoming a bit softer or more watery. If you plan to freeze, bake the casserole without the cracker topping. Allow it to cool completely, then wrap it tightly in plastic wrap and aluminum foil before freezing for up to 2-3 months. Thaw overnight in the refrigerator, then add the fresh cracker topping and bake as directed, adding extra time if needed. For best results, it’s often better to enjoy it fresh or stored in the refrigerator.

What kind of baking dish is best?

A 9×9 inch square glass baking dish works perfectly for this recipe, allowing for even cooking and browning. Ceramic or cast-iron baking dishes of a similar size can also be used. If you’re using a different material, just keep in mind that baking times might vary slightly, so keep an eye on the casserole for doneness.

Close up photo of Squash Casserole in a dish, showing its rich, golden-brown crust

Serving Suggestions for Your Delicious Casserole

Squash casserole is incredibly versatile and makes an awesome side dish that can be enjoyed year-round, not just during specific seasons. It’s truly a star accompaniment to a wide variety of main courses.

Holiday Feasts: This casserole is a perennial favorite for Thanksgiving, Christmas, or Easter. It pairs beautifully with traditional holiday mains like roasted turkey, glazed ham, or a succulent prime rib roast. Its rich flavors and comforting presence complement the festive spread.
Weeknight Dinners: Elevate a simple weeknight meal by serving this casserole alongside grilled chicken, baked fish, or pork chops. It adds a touch of homemade goodness without a lot of fuss.
Hearty Mains: For a more substantial meal, consider pairing it with robust protein dishes such as tender spatchcock chicken, flavorful sirloin pork roast, or an elegant beef tenderloin. The creamy and cheesy notes of the casserole cut through the richness of these meats beautifully.
Potlucks and Gatherings: Its crowd-pleasing nature makes it an ideal dish for potlucks, family reunions, or any gathering where you need a reliable and delicious side. It travels well and is always a hit!
Vegetarian Main Course: Believe it or not, with its creamy, cheesy goodness, this casserole can even stand alone as a light vegetarian main dish when served with a fresh green salad.

Explore More Delicious Squash Recipes

If you’ve fallen in love with the versatility and flavor of squash, you’re in luck! There are many other fantastic ways to incorporate this healthy and delicious vegetable into your diet. Here are some of our favorite squash-based recipes to inspire your next meal:

Zucchini Casserole: Another cheesy, comforting casserole, perfect for using up garden zucchini.
Air Fryer Acorn Squash: A quick and easy way to enjoy the sweet, nutty flavor of acorn squash with minimal effort.
Baked Spaghetti Squash: A healthy and low-carb alternative to pasta, great for various sauces.
Butternut Squash Mac and Cheese: A creamy, vibrant twist on a classic comfort food, packing in extra vegetables.
Slow Cooker Butternut Squash Soup: A warm and inviting soup that practically makes itself, perfect for a chilly day.

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Close up photo of a heaping spoonful of Squash Casserole

Squash Casserole Recipe

Simple, satisfying, and incredibly comforting – this yellow squash casserole is a perfect dish for both holiday feasts and casual summer parties!

5 from 1 vote

IMPORTANT – Don’t forget to scroll up to the blog post for frequently asked questions and expert tips that you may find incredibly helpful!

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Ingredients

6 medium yellow squash, sliced 1/4 inch thick
1 med-large yellow onion, chopped
⅓ cup water
2 cups sharp cheddar cheese, shredded
1 ½ cups sour cream, full-fat
2 large eggs
½ teaspoon sea salt (more to taste)
½ Tablespoon fresh thyme
¼ teaspoon ground black pepper
½ cup parmesan cheese, grated
30 Ritz crackers, crushed
½ cup unsalted butter, melted (1 stick)

Things You’ll Need

9×9 baking dish
Mixing bowls

Before You Begin (Important Notes & Tips)

Choose squash that are firm and feel heavy with shiny skin.
You do not need to peel the squash for this recipe. The skin actually helps keep the squash rounds intact after being baked.
You can substitute the sharp cheddar with mild or extra sharp if desired. Easily swap out the cheddar entirely and go with your favorite kind of cheese, or a blend of the two.
The Ritz crackers can be substituted with breadcrumbs or saltines if preferred.
Squash has a high water content, which will shine through in the finished casserole if you don’t drain it well enough before combining it with the other ingredients. You’ll want to try and remove as much excess water as possible both during the sautéing process and when you drain them afterward. Keep in mind the squash will still continue to cook in the oven after sautéing so don’t overcook them in the skillet, as this can cause them to become mushy and watery.

Instructions

Preheat the oven to 400°F (200°C) and lightly grease a 9×9 inch square glass baking dish.
Cook the squash and onion in a large pan with 1/3 cup water on medium-high heat for about 8-10 minutes or until soft. Strain any excess water before placing them in a large mixing bowl.
TIP – You may want to allow the squash to sit in the strainer for a few minutes to get the majority of the water out, and lightly press them down without squishing them.
In a medium bowl, mix together the cheddar cheese, sour cream, eggs, salt, thyme, and ground black pepper. Pour into the bowl with the squash and combine well. If it becomes very liquidy, you can drain some out.
Transfer to the prepared baking dish and cover with ¼ cup parmesan cheese.
In a small bowl, combine the crushed Ritz crackers and melted butter well. Sprinkle an even layer on top and bake for about 15 minutes or until bubbling and golden.
Garnish with more fresh thyme and enjoy.

Expert Tips & FAQs

Store any cooled leftovers in an air-tight container kept in the refrigerator for up to 4 days. Reheat in a 350°F (175°C) oven until warmed through.
To Make Ahead: Prepare the casserole without the cracker topping a day in advance and store it, covered, in the refrigerator. Allow the casserole to rest at room temp while the oven preheats (or slightly longer if you are using a glass dish) then proceed with recipe instructions. You may need to add a few extra minutes in the oven if it’s going in cold.

Nutrition Facts (per serving)

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The recipes on this blog are tested with a conventional gas oven and gas stovetop. It’s important to note that some ovens, especially as they age, can cook and bake inconsistently. Using an inexpensive oven thermometer can assure you that your oven is truly heating to the proper temperature. If you use a toaster oven or countertop oven, please keep in mind that they may not distribute heat the same as a conventional full sized oven and you may need to adjust your cooking/baking times. In the case of recipes made with a pressure cooker, air fryer, slow cooker, or other appliance, a link to the appliances we use is listed within each respective recipe. For baking recipes where measurements are given by weight, please note that results may not be the same if cups are used instead, and we can’t guarantee success with that method.