Yellow Squash Casserole

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This Yellow Squash Casserole is the ultimate comforting summer side dish. It’s made with tender squash baked in a creamy sauce and topped with buttery crackers. Our casserole recipe is easy to prepare and uses up all that extra summer squash!

Squash casserole on a white plate.

Easy Summer Squash Casserole

There are plenty of ways to enjoy yellow squash. But, in my opinion, this Old Fashioned Yellow Squash Casserole is hands down the best way to serve it.

I mean, who doesn’t love fork-tender squash smothered in a rich, creamy, cheesy sauce, topped with the buttery crunch of crushed Ritz crackers? 

It really is a comfort food you’ll be wanting to make over and over again!

How to Make Yellow Squash Casserole with Ritz Crackers

This easy squash casserole recipe takes a quick 15 minutes to prep before you can pop it in the oven! 

Scroll to the recipe card below for ingredient amounts and full instructions.

  1. Heat oil in a large skillet, then add in the squash and onions. Cook until softened, then remove from the heat.
  2. In a bowl, combine the mayonnaise, egg, cheese, flour, and seasonings. Add in the squash and onions and stir to coat. Transfer to a greased baking dish.
Top down view of cooked yellow squash in a pan.
Top down view of squash casserole filling in a bowl.
  1. In another bowl, combine crushed crackers, parmesan cheese, and melted butter. Sprinkle over the top of the squash mixture in the baking dish.
  2. Place the assembled casserole in the oven and bake until golden-brown and bubbly. Cool for 10-15 minutes, then serve. 
Top down view of squash casserole in a baking dish.
Top down view of a baking dish filled with squash casserole and crushed crackers.

Tips and Variations

  • Shred your own cheese. Pre-shredded cheeses contain an anti-caking agent that can result in a gritty or grainy texture when melted. For the best results, shred fresh cheese right off the block. 
  • Rounds vs. cubes: I usually chop the squash into 1-inch cubes, but if you’re looking for a slightly different texture, you can slice the squash into rounds instead. You can do this with a mandolin slicer or a knife.
  • Spice it up. Give your casserole a kick of heat by mixing in freshly diced jalapeños, canned green chiles, cayenne pepper, or red pepper flakes. 
  • Swap the topping. The Ritz crackers are delicious, but you can also use saltine crackers, oyster crackers, breadcrumbs, or even crushed up potato chips.
  • Add a protein. Want to make your baked squash casserole into more of a meal? Try adding in canned and drained tuna or cooked and shredded chicken. 
  • Use another cheese. I love the flavor combination of the sharp cheddar and parmesan, but you can use any salty cheese you prefer. Try pepper jack, pecorino romano, gruyere, you name it.

Serving Suggestions

This summer squash casserole is a hit for summer, so we love to serve it as a side dish alongside classic summer entrees! Here are a few pairing ideas:

Yellow squash casserole on a white serving plate.

Make-Ahead and Storage Instructions

Make-Ahead: To prep this casserole ahead of time, you can cook the squash and onion, fully assemble the casserole, then cover and store in the fridge up to a day in advance. When you’re ready to serve, simply remove the plastic wrap and bake as directed. You may need to add a little bit of baking time to ensure it gets heated all the way through.

Refrigerator: Leftover summer squash casserole can be stored covered or wrapped tightly in plastic wrap in the fridge for 4-5 days. 

Reheating: To reheat leftover casserole, simply bake it in the oven at 350ºF until heated all the way through. Alternatively, you can warm single servings in the microwave, but the Ritz cracker topping won’t be as crispy.

Freezer: I do not recommend freezing yellow squash casserole. The texture of the squash will not hold up well when thawed.

Do You Need to Remove the Skin from Yellow Squash?

Nope, there’s no need! The skin on summer squash is super soft, especially when it’s cooked. So, you can leave it on and it cooks up just fine for the casserole. There’s no need for the extra step.

How Do You Keep Squash Casserole from Getting Watery?

The key to preventing a watery casserole is to pre-cook the veggies!

As they cook, veggies—particularly squash—release a lot of moisture. Pre-cooking them is an essential step because it releases that excess moisture from the veggies before they go into the casserole. 

More Comforting Casserole Recipes to Try

Looking for more classic casserole recipes? Here are a few favorites!

Like This Recipe?

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Yellow squash casserole served on a white plate.

Old Fashioned Yellow Squash Casserole

4.5 from 28 votes
Print Pin
Author: Kimberly
Prep Time: 15 minutes
Cook Time: 35 minutes
Cooling Time: 15 minutes
Total Time: 1 hour 5 minutes
Servings: 12 Serving

Ingredients

Squash Casserole Filling

  • 1 tablespoon olive oil
  • 2 yellow squash, cut into 1-inch pieces (about 4 to 5 cups)
  • 1 cup white onion, diced
  • 1 cup mayonnaise
  • 1 large egg
  • 1 cup sharp 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

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

Instructions
 

To Make the 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.
    1 tablespoon olive oil
    2 yellow squash
    1 cup white onion
  • 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. 
    1 cup mayonnaise
    1 large egg
    1 cup sharp cheddar cheese
    ½ cup Parmesan cheese
    1 tablespoon all-purpose flour
    1 teaspoon garlic powder
    Salt and pepper
  • Transfer the squash mixture to the prepared baking dish.

To Make the Cracker Topping:

  • In a separate small bowl, combine the crushed crackers, Parmesan cheese, and melted butter.
    1 cup butter crackers
    ¼ cup Parmesan cheese
    2 tablespoons unsalted 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.
  • Scroll up and see the post for tips, FAQs, and storage recommendations.

Nutrition

Serving: 0.5cup | Calories: 260kcal | Carbohydrates: 7g | Protein: 6g | Fat: 23g | Saturated Fat: 7g | Polyunsaturated Fat: 9g | Monounsaturated Fat: 6g | Trans Fat: 0.2g | Cholesterol: 40mg | Sodium: 346mg | Potassium: 137mg | Fiber: 1g | Sugar: 2g | Vitamin A: 299IU | Vitamin C: 7mg | Calcium: 161mg | Iron: 1mg

Notes

*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.
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