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This summer yellow squash casserole is the quintessential summertime vegetable casserole recipe. It’s packed with yellow squash, onion, garlic, cheese, and sour cream and topped with buttery crackers.
Our childhood garden grew A LOT of summer squash and zucchini, often overflowing. If you have ever had a garden, you know this plight.
We made everything from summer squash pancakes to grilled squash to the classic chocolate zucchini bread. Pro tip: you can use yellow squash where you would use zucchini. That means classic zucchini bread can be made with yellow summer squash.
But back to this creamy casserole. I think of it as a Southern/Appalachian/Midwest specialty. There is a lot of overlap in the food department in these regions.
It all starts by gently sauteing the squash to remove excess moisture. This is essential to ensure the casserole doesn’t get watery and holds together. Plus, it gives time for the onion and garlic to cook out some of their more robust flavors.
After that, it’s mixed with delicious filling ingredients and topped with buttery crushed crackers. It’s the perfect summer casserole. And the ideal way to use up all that fresh yellow squash.
While this is the perfect summer recipe, yellow squash casserole is also great as a holiday side dish. Especially because you can easily find yellow squash year-round.
Ingredients needed
- Yellow squash
- Yellow onion
- Garlic
- Olive oil
- Eggs
- Sour cream
- Shredded cheddar cheese
- Spices
- Butter
- Butter crackers (Ritz)
How to make squash casserole
We all know I love a casserole recipe, and I’m guessing you do too! If this is your first time making squash casserole, you’ll LOVE how easy it is!
- Saute the squash, onion, and garlic together. Once soft, add them to a colander and let them drain while you make the second step of your filling.
- Whisk together eggs, sour cream, cheddar cheese, and spices.
- Stir in the drained and slightly cooled squash mixture.
- Add to a 9×13 baking dish and top with buttery Ritz crackers.
- Bake until golden brown and warmed throughout.
My Pro Tips
Recipe Tips
- For this recipe, you want to slice your squash and onion very thinly. I suggest using a mandoline. Just watch your fingers!
- You can make this casserole ahead of time, cover it with plastic wrap, and store it in the fridge, but don’t top it with the crackers until right before you bake.
- Use fresh squash without soft spots or cuts in the skin.
- Don’t overcook your squash when sauteing. You’re only looking to cook out some of the moisture.
- Let your squash thoroughly drain before mixing it with the egg mixture.
- Serve alongside 3-Ingredient Instant Pot Ham, Air Fryer Chicken Legs, Stuffed Pork Tenderloin, or my BBQ Shredded Beef (Sandwiches).
Substitutions and Adaptations
I love lightly experimenting with savory recipes; you all feel the same! Here are a few changes you can make to jazz up this southern squash casserole.
- Some like to steam their squash/onion/garlic mixture for 10-15 minutes rather than sauteing it. I think sauteing gives it more depth of flavor, but both options are good. Just remember that both options need to be drained in the colander.
- Try using pepper Jack, Gruyere, or Colby Jack cheese to switch up on the classic sharp cheddar cheese.
- Add red bell pepper or spicy jalapeno pepper for flavor and kick.
- Instead of just sour cream, you can use 1/4 cup of sour cream and 1/4 cup of mayonnaise.
- Use bread crumbs, crushed potato chips, or panko bread crumbs instead of buttery Ritz crackers.
- Add in spices like thyme, paprika, or fresh parsley.
- You can use half yellow squash and half zucchini if desired.
More squash recipes
Yellow Squash Casserole
Ingredients
- 2 tablespoons olive oil
- 3 pounds yellow squash, thinly sliced
- 1 large yellow onion, thinly sliced
- 2 cloves garlic, minced
- 2 large eggs
- 1 cup shredded cheddar cheese, divided
- ½ cup sour cream
- ½ teaspoon kosher salt
- ½ teaspoon black pepper
- ½ teaspoon Italian seasoning
- 3 tablespoons salted butter
- 1 sleeve butter crackers, Ritz, 30-32 crackers
Instructions
- Preheat your oven to 375 degrees F and spray a 9×13 casserole dish with non-stick spray.
- In a 12-inch high-sided skillet set over medium-high heat, add olive oil.
- When the oil is hot, add the thinly sliced squash and onion. Saute gently until the squash is soft but not falling part. You want to cook out the liquid but you're not looking to brown the squash or the onion. This step will take about 10 minutes.
- Add in the garlic and saute for 1 minute.
- Spoon the squash mixture into a fine mesh colander set over a bowl or the sink. Gently push on the squash to help it drain any remaining water. This step helps prevent the casserole from becoming too watery while baking.
- While the squash drains, work on the second step of your filling.
- In a large bowl, whisk the eggs and then whisk in 1/2 cup shredded cheese, sour cream, kosher salt, black pepper, and Italian seasoning.
- Add the drained squash mixture to the egg/sour cream mixture and stir gently to combine.
- Add the squash mixture to the prepared pan.
- In a small bowl, mix together the melted butter and crushed butter crackers until evenly coated.
- Top the casserole with 1/2 of the cracker mixture, then sprinkle with remaining 1/2 cup of shredded cheddar cheese, and then the rest of hte cracker mixture.
- Add to the preheated oven and bake for 35 minutes or until the top is golden brown and toasted.
- Serve warm, store leftovers in a covered container, and eat within 3-4 days.
Nutrition
Nutrition information is automatically calculated, so should only be used as an approximation.
This is my favorite way to use up the abundance of squash from my garden! It’s always a hit with my family!