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My uncle swore up and down at every family reunion that he hated squash. And every year, he went back for seconds of my mother’s squash casserole. She never said a word, she just watched him do it. Southern squash casserole was on every potluck table in the South: tender yellow squash and onion, folded together with sharp cheddar and sour cream and bound with an egg, under a thick, buttery cracker crumb topping that bakes golden and crunchy. It is creamy and cheesy and tastes far better than a dish of squash has any right to.
The one problem everybody has with squash casserole is water. Yellow squash is mostly water, and if it goes into the dish straight from the pot, it leaks into the custard in the oven and leaves a puddle in the bottom of the dish. My mother’s secret was simple: after cooking the squash, she drained it in a colander and pressed it until no more liquid ran out. Here is how to keep squash casserole from being watery, so it comes out creamy and set every time.
Why this squash casserole works
- Squash cooked, then pressed dry. Pressing out the water is the single step that keeps the casserole creamy instead of soupy.
- Onion cooked with the squash. It turns soft and sweet and seasons the squash from the inside.
- Sharp cheddar and sour cream. Sharp cheddar gives real flavor, and sour cream makes it rich and tangy.
- One egg. The egg sets the filling into a soft custard so it holds together on a spoon.
- Butter-tossed cracker crumbs. Crushed crackers stirred into melted butter bake into a crunchy golden lid.
Ingredients
Makes one 2 quart casserole, about 8 servings. The measurements are in US cups with grams in brackets.
For the squash
- 2 pounds yellow summer squash, sliced 1/4 inch thick (900g, about 6 medium)
- 1 medium onion, chopped
- 1/2 cup water (120ml)
- 1 teaspoon fine salt
For the filling
- 1 1/2 cups shredded sharp cheddar (170g), divided
- 1/2 cup full-fat sour cream (120g)
- 1 large egg, beaten
- 2 tablespoons butter, melted
- 1/2 teaspoon black pepper
- 1/4 teaspoon garlic powder
For the topping
- 1 1/2 cups crushed round butter crackers (about 36 crackers, 110g)
- 4 tablespoons butter, melted (55g)
Choose small to medium squash with smooth skins. Big squash are seedy and watery. Any plain buttery round crackers or saltines work for the topping.
How to make squash casserole
- Heat the oven to 350 degrees (175°C). Butter a 2 quart baking dish.
- Put the squash, onion, water and salt in a large pot. Cover and cook over medium heat for 10 to 12 minutes, stirring once or twice, until the squash is very tender.
- Tip the squash into a colander set in the sink and let it drain for 5 minutes.
- Press the squash firmly with the back of a big spoon or a potato masher, pressing out as much liquid as you can. Keep pressing until it stops running. The squash will break up, and that is fine.
- Move the drained squash to a large bowl and let it cool for 5 minutes.
- Stir in 1 cup of the cheddar, the sour cream, the egg, the melted butter, pepper and garlic powder. Taste and add a pinch more salt if needed.
- Spread the mixture in the baking dish.
- Stir the crushed crackers with the 4 tablespoons of melted butter until evenly moistened. Scatter the remaining 1/2 cup of cheddar over the squash, then the buttered crumbs on top.
- Bake for 30 to 35 minutes, until the edges are bubbling, the center is set and the topping is deep golden.
- Let it rest for 10 minutes before serving so it firms up.
Tips that make the difference
- Pressing the squash is the whole secret. If you skip it, the casserole will be watery no matter what else you do.
- Let the squash cool a little before adding the egg so the egg does not scramble.
- For an extra crisp top, run the dish under the broiler for 1 to 2 minutes at the end, watching it closely.
- Shred your own cheddar. It melts smoother than the pre-shredded kind.
Variations
- Zucchini. Use half zucchini and half yellow squash.
- Squash dressing. Stir 2 cups of crumbled cornbread into the filling, the way many Southern families make it.
- Bread crumb top. Use buttered fresh bread crumbs instead of crackers.
- A little heat. Add a chopped green chile or a pinch of cayenne to the filling.
Storage and make-ahead
Refrigerate leftovers, covered, for up to 3 days. Reheat in a 350 degree oven for 15 to 20 minutes.
Assemble it up to a day ahead without the topping, refrigerate, then add the crumbs and bake, giving it 5 to 10 extra minutes.
It does not freeze well. Thawed squash turns watery.
Frequently asked questions
Why is my squash casserole watery?
The squash was not drained and pressed. Squash is mostly water, so press it in a colander until no more liquid runs out before mixing.
Can I use frozen squash?
Yes. Thaw it, then press out the water very well. Frozen squash holds even more water than fresh.
Is it squash casserole or squash dressing?
Squash dressing usually has cornbread stirred in. Squash casserole is the creamy, cheesy version with a cracker top.
Can I make it without sour cream?
Use the same amount of plain full-fat yogurt or cream cheese softened with a little milk.
Put it on the table next to the fried chicken and do not tell anybody it is squash. Let them find out after the second helping.
Southern Squash Casserole (Cheesy, Buttery Cracker Top, Never Watery)
Old-fashioned Southern squash casserole: tender yellow squash and onion folded with sharp cheddar, sour cream and an egg, baked under a buttery cracker crumb topping until golden and set, never watery.
Ingredients
- 2 pounds yellow summer squash, sliced 1/4 inch thick
- 1 medium onion, chopped
- 1/2 cup water
- 1 teaspoon fine salt
- 1 1/2 cups shredded sharp cheddar (170g), divided
- 1/2 cup full-fat sour cream
- 1 large egg, beaten
- 2 tablespoons butter, melted
- 1/2 teaspoon black pepper
- 1/4 teaspoon garlic powder
- 1 1/2 cups crushed round butter crackers
- 4 tablespoons butter, melted
Instructions
- Heat the oven to 350 degrees (175°C). Butter a 2 quart baking dish.
- Put the squash, onion, water and salt in a large pot. Cover and cook over medium heat for 10 to 12 minutes, stirring once or twice, until the squash is very tender.
- Tip the squash into a colander set in the sink and let it drain for 5 minutes.
- Press the squash firmly with the back of a big spoon or a potato masher, pressing out as much liquid as you can. Keep pressing until it stops running. The squash will break up, and that is fine.
- Move the drained squash to a large bowl and let it cool for 5 minutes.
- Stir in 1 cup of the cheddar, the sour cream, the egg, the melted butter, pepper and garlic powder. Taste and add a pinch more salt if needed.
- Spread the mixture in the baking dish.
- Stir the crushed crackers with the 4 tablespoons of melted butter until evenly moistened. Scatter the remaining 1/2 cup of cheddar over the squash, then the buttered crumbs on top.
- Bake for 30 to 35 minutes, until the edges are bubbling, the center is set and the topping is deep golden.
- Let it rest for 10 minutes before serving so it firms up.
