Yellow Squash Casserole
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Yellow Squash Casserole is the dish I bring to every potluck and come home with an empty pan every time. The filling is thick, cheesy, and savory with sharp cheddar and sour cream folded around tender roasted squash. The buttery cracker crust made with crushed Ritz bakes up golden and crunchy. Warm, hearty, and the kind of thing everyone asks you to make again.
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I make it for Thanksgiving spreads, Easter dinners, and summer potlucks when yellow squash is at its peak and I want a side dish that feeds a crowd without any fuss. It’s also a great make-ahead casserole since it reheats beautifully. Store leftovers covered in the fridge for up to 3 days and reheat in the oven to revive that golden topping.
Ingredients You’ll Need
You’ll need all the ingredients shown in the photograph below.
How to Make Yellow Squash Casserole with Step-By-Step Instructions
Scroll down for the full recipe card containing a full printable recipe and measurements in both US customary and metric units.
Here’s how to put together the best squash casserole recipe from start to finish that turns out creamy and perfectly golden-topped.
Roast the Squash and Onion
Preheat your oven to 350°F (180°C). On a large rimmed roasting sheet pan, drizzle the sliced yellow squash and chopped onion with olive oil, then season with kosher salt and pepper. Toss everything together until the sliced squash and onion are evenly coated.
Spread them across the pan in a single layer, then slide the pan into the oven and roast for 20 to 25 minutes until the squash is tender. Once it comes out, drain the fresh squash mixture thoroughly in a stainless steel colander or pat it dry with paper towels to remove excess liquid.
This step is important because summer squash holds a lot of moisture, and draining it prevents a watery casserole. Let it cool slightly before moving on.
Mix the Creamy Squash Filling
In a large bowl, add eggs and whisk until smooth. Add the mayonnaise, sour cream, finely shredded cheddar cheese, fresh thyme, and cayenne pepper, then gently fold in the cooled squash mixture until everything is just combined.
Pour the squash-egg mixture into a prepared baking dish and bake in the preheated oven at 350°F for about 20 minutes, until it begins to set, softens through, and turns lightly browned. A ceramic baking dish heats evenly, preventing uneven hot spots in your casserole.
Make the Ritz Cracker Topping
While the filling bakes, combine the crushed Ritz cracker crumbs, vegetarian Parmesan cheese, and melted butter in a small bowl, stirring until the crushed crackers are well coated. I use the fine-holed side of my box grater to finely grate my own blocks of cheese for the best melt.
Once the filling has had its initial 20 minutes in the oven, pull the casserole dish out and sprinkle the cracker mixture evenly over the top of your cooked squash-cheese mixture.
Bake Until Golden and Bubbly
Return the casserole to the oven and bake for another 25 to 30 minutes until the topping is deep golden brown and the cheese underneath is melted and bubbling around the edges. Let it rest for 2 to 3 minutes before serving so the filling has a chance to settle slightly.
Enjoy your hearty squash casserole!
Yellow Squash Casserole holds up beautifully at room temperature for a few hours and travels well to potlucks or family gatherings. Once fully cooled, cover the dish tightly with foil or a fitted silicone casserole lid, then transport it in an insulated carrier to keep it warm.
Ingredients
- 3 pounds yellow squash sliced
- 1 onion chopped
- 3 tablespoons olive oil
- 1 teaspoon Kosher salt
- ¾ teaspoon black pepper
- 2 eggs
- ½ cup mayonnaise
- 8 ounces sour cream
- 8 ounces Cheddar cheese sharp
- 1 tablespoon thyme fresh
- ¼ teaspoon cayenne pepper
- 40 Ritz crackers crushed
- ¼ vegetarian Parmesan cheese
- ½ cup butter
Video
Instructions
- Pre heat your oven to 350°F (180°C).
- In a large rimmed baking sheet add the squash, onion, olive oil, salt, black pepper and toss to combine. Cook until tender for approximately 20-25 minutes. Completely drain the squash mixture and set aside to cool slightly.3 pounds yellow squash, 1 onion, 3 tablespoons olive oil, 1 teaspoon Kosher salt, ¾ teaspoon black pepper
- In a large bowl whisk the eggs, then add mayonnaise, sour cream, cheddar cheese, thyme and cayenne pepper and gently fold in the cooled squash mixture. Now add it into your prepared casserole dish and cook until softened for approx. 20 minutes.2 eggs, ½ cup mayonnaise, 8 ounces sour cream, 8 ounces Cheddar cheese, 1 tablespoon thyme, ¼ teaspoon cayenne pepper
- Meanwhile, in a smaller bowl add the crushed Ritz cracker crumbs, vegetarian parmesan cheese and pour in the melted butter. Now sprinkle the Ritz cracker crumbs over the top of your cooked squash mixture.40 Ritz crackers, ¼ vegetarian Parmesan cheese, ½ cup butter
- Cook for a further 25-30 minutes until the top is golden brown and the cheese is melted and bubbly. Allow to cool for 2-3 minutes, then serve. Enjoy your hearty squash casserole!
Notes
Nutrition
How to Store Leftovers
Let the casserole cool completely before covering the dish tightly with plastic wrap or transferring leftovers to an airtight container. It keeps well in the refrigerator for up to 3 days.
To reheat, pop individual portions in the microwave or warm the whole dish in the oven at 325°F, uncovered, until heated through, which helps bring the cracker topping back to life.
To freeze, skip the crackers on top, as they lose their crunch and make a soggy casserole topping once thawed. Wrap portions tightly in plastic wrap and then in foil before placing them in a freezer-safe container.
You can freeze squash casserole for up to 3 months, so you can make it ahead of time. Take the frozen squash casserole out of the freezer and thaw overnight in the fridge, then add the cracker topping fresh as you reheat it in the oven for best results.
What to Serve With Yellow Squash Casserole
It works as a hearty vegetarian main or a side alongside roasted green beans, a fresh corn salad, or glazed carrots. It also pairs really well with a bowl of tomato soup or a light pasta dish.
A simple green salad with a bright vinaigrette cuts through the richness beautifully, and some warm crusty bread alongside is never a bad idea for scooping up the creamy filling.
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This was comfort food at its finest…SO delicious! Can’t wait to have it again already!