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Baked southern summer squash casserole in a white baking dish with tender yellow squash, cheddar cheese, and a buttery cracker topping.

Southern Summer Squash Casserole

Southern Summer Squash Casserole is the kind of cozy side dish that makes a simple dinner feel a little more special. Tender yellow summer squash and sweet onion are cooked until soft, folded into a creamy cheddar filling, and baked with a buttery Ritz cracker topping until golden and bubbling around the edges.
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Prep Time 30 minutes
Cook Time 35 minutes
Total Time 1 hour 5 minutes
Servings: 8
Course: Casserole
Cuisine: Southern
Ingredients Method Notes

Ingredients
  

  • 2-1/2 pounds yellow summer squash, about 6 to 7 medium squash, sliced into 1/4-inch rounds
  • 1 medium sweet onion, diced
  • 3 tablespoons butter
  • 1 teaspoon kosher salt, divided
  • 1/2 teaspoon black pepper
  • 1/2 teaspoon garlic powder
  • 3/4 cup sour cream
  • 1/4 cup mayonnaise
  • 2 large eggs, lightly beaten
  • 2 cups freshly shredded sharp cheddar cheese, divided
  • 1 sleeve Ritz crackers, crushed
  • 3 tablespoons melted butter

Method
 

  1. Preheat the oven to 350°F. Grease a 9x13-inch baking dish with butter or nonstick spray.
  2. Melt 3 tablespoons butter in a large skillet or Dutch oven over medium heat. Add the sliced squash, diced onion, and 1/2 teaspoon kosher salt. Cook for 12 to 15 minutes, stirring occasionally, until the squash is tender and has released a good amount of liquid.
  3. Transfer the squash and onion mixture to a colander. Drain for 5 to 10 minutes, then gently press with the back of a spoon or spatula to remove excess moisture.
  4. In a large mixing bowl, stir together the sour cream, mayonnaise, beaten eggs, black pepper, garlic powder, and remaining 1/2 teaspoon kosher salt.
  5. Add the drained squash mixture, 1 1/2 cups shredded cheddar cheese, and 1/2 cup crushed Ritz crackers. Fold gently until combined.
  6. Spread the mixture into the prepared baking dish. Sprinkle the remaining 1/2 cup cheddar cheese over the top.
  7. In a small bowl, stir the remaining crushed Ritz crackers with 3 tablespoons melted butter. Sprinkle evenly over the casserole.
  8. Bake uncovered for 30 to 35 minutes, until the casserole is hot, set in the center, bubbling around the edges, and golden brown on top.
  9. Let rest for 10 minutes before serving.

Notes

Use yellow summer squash for the most classic Southern flavor and color.
Do not skip draining the cooked squash. This step keeps the casserole from turning watery.
Freshly shredded sharp cheddar melts better than bagged shredded cheese and gives the casserole a smoother texture.
For a softer, old-fashioned texture, lightly mash part of the cooked squash after draining. For more visible squash slices, leave the squash mixture as-is.
This casserole is best served fresh or refrigerated and reheated. Freezing is not recommended because summer squash softens after thawing.