Yellow Squash Casserole

updated Nov 13, 2023

Squash casserole is a classic side dish, with mild yellow squash in a creamy cheddar sauce and topped with a crunchy cracker topping.

Serves8

Prep20 minutes

Cook30 minutes to 40 minutes

Jump to Recipe
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If your vegetable drawer is still stuffed with squash after you’ve already grilled it, made gratin, or packed it into a quick bread, it’s time to take a cue from Southern potlucks and holiday spreads, and make a cheesy yellow squash casserole. 

Squash casserole is a classic meat-and-three side dish in which mild yellow squash is baked in a creamy cheddar cheese sauce, and topped with a buttery cracker topping. Here’s how to make a squash casserole that will have everyone asking for seconds.

Key Ingredients in Squash Casserole

  • Yellow squash: Also called summer or crookneck squash, yellow squash has a mild flavor and tender, edible skin.
  • Sweet onion: Vidalia and Walla Walla are the most common sweet onions. They are sweeter and less astringent than other types of onions.
  • Cheddar cheese: Whisk sharp cheddar cheese into the sauce and save some to sprinkle on top with buttery crackers.
  • Round butter crackers: Toast crushed crackers in melted butter before topping the casserole. 
Credit: Kelli Foster

How to Choose the Best Yellow Squash

Yellow squash is available year-round in the grocery store, but the summer months are when these vegetables are at their finest. Summer squash has a thinner skin than their winter kin, so there’s no need to peel before adding them to this casserole. 

Handle the squash gently and look for squash that have no blemishes or soft spots. Choose slender, uniformly sized squash for best flavor and smaller seeds. While you can use any fresh summer squash in this casserole, yellow squash is traditional.

Credit: Kelli Foster

How To Prevent a Watery Casserole

Yellow squash can release a lot of moisture into casseroles if you aren’t careful. There are two ways to prevent a watery casserole.

  • Sauté squash before baking. Slice yellow squash to expose more surface area, then sauté with another Southern staple, sweet onions, until moisture is released, and the squash are just tender. 
  • Drain after sautéing. Transfer squash with a slotted spoon to a colander, discarding any excess moisture in the skillet. Let the squash drain for five minutes. 

How To Make Squash Casserole

  • Sauté yellow squash and sweet onion. Cook sliced yellow squash and diced sweet onion in butter until tender and some moisture is released.
  • Drain squash and onions. Prevent a watery casserole by letting the squash and onions drain for five minutes before adding to the sauce.
  • Make the sauce. Whisk eggs, cheddar cheese, milk, mayonnaise, and cayenne pepper until combined.
  • Add yellow squash and onions to the sauce. Coat yellow squash and onions in the sauce, then transfer to a 9×13-inch baking dish.
  • Toast crackers in butter. Melt butter in the skillet and toss with crushed crackers until coated. 
  • Top the casserole. Scatter shredded cheese over the squash mixture then top with butter-toasted crackers for a crispy, cheesy topping. 
  • Bake the squash casserole. Bake until the squash casserole is browned and bubbly.

What To Serve with Squash Casserole

Yellow squash casserole is a year-round staple, from summer cookouts to holiday gatherings. Here are some recipes to serve with squash casserole. 

Yellow Squash Casserole Recipe

Squash casserole is a classic side dish, with mild yellow squash in a creamy cheddar sauce and topped with a crunchy cracker topping.

Prep time 20 minutes

Cook time 30 minutes to 40 minutes

Serves 8

Nutritional Info

Ingredients

  • 2 pounds

    yellow summer squash (about 4 medium)

  • 1

    medium sweet onion, such as Vidalia

  • 8 ounces

    sharp cheddar cheese

  • 6 tablespoons

    (3/4 stick) unsalted butter, divided, plus more for the baking dish

  • 3/4 teaspoon

    kosher salt

  • 1/2 teaspoon

    freshly ground black pepper

  • 2

    large eggs

  • 1/4 cup

    whole or 2% milk

  • 1/4 cup

    mayonnaise

  • 1/4 cup

    sour cream

  • 1/4 teaspoon

    cayenne pepper

  • 45

    round butter crackers, such as Ritz ( about 1 1/2 sleeves)

Instructions

  1. Arrange a rack in the middle of the oven and heat the oven to 350°F. Coat a 9x13-inch baking dish with butter.

  2. Trim and slice 2 pounds yellow squash into 1/4-inch thick rounds (about 7 cups). Dice 1 medium sweet onion (about 1 1/2 cups). Grate 8 ounces sharp cheddar cheese on the large holes of a box grater (about 2 cups).

  3. Melt 2 tablespoons of the unsalted butter in a 12-inch or larger skillet over medium heat. Add the squash, onion, 3/4 teaspoon kosher salt, and 1/2 teaspoon black pepper. The skillet will be quite full. Cook, stirring occasionally, until tender and just beginning to brown, about 10 minutes.

  4. Transfer the squash and onions to a colander set over a bowl or placed in the sink; reserve the skillet. Set aside to drain for 5 minutes.

  5. Place 2 large eggs, 1/4 cup whole or 2 % milk, 1/4 cup mayonnaise, 1/4 cup sour cream, 1/4 teaspoon cayenne pepper, and half of the cheese in a large bowl and whisk to combine.

  6. Transfer the squash and onions into the egg mixture. Stir to coat the vegetables in the sauce. Transfer to the baking dish and spread into an even layer. Sprinkle with the remaining 1 cup cheese.

  7. Place 45 round butter crackers in a large zip-top plastic bag and seal the bag. Use your hands to crush into coarse crumbs (about 2 1/4 cups).

  8. Melt the remaining 4 tablespoons unsalted butter in the reserved skillet over medium heat. Add the crackers and stir to coat. Evenly sprinkle the cracker crumbs over the casserole.

  9. Bake until browned and the edges bubble, 25 to 30 minutes. Let cool for 5 minutes before serving.

Recipe Notes

Ingredient variation: Zucchini can be substituted for the yellow squash.

Make ahead: The casserole can be assembled without the cracker topping, covered, and refrigerated up to 2 days in advance. Remove the casserole from the refrigerator while the oven heats and make the cracker topping. Bake until browned and bubbling, 30 to 35 minutes.

Storage: Refrigerate leftovers in an airtight container for up to 4 days.