Southern Yellow Squash Casserole

Water clinging to cooked squash can turn a casserole loose before the top has time to brown. I drain the squash and onion, then give them a few quiet minutes…

By Riley • November 1, 2026 • Reading time: 8 min

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Water clinging to cooked squash can turn a casserole loose before the top has time to brown. I drain the squash and onion, then give them a few quiet minutes in the colander before they meet the creamy filling. That small pause helps make Southern Yellow Squash Casserole scoopable instead of soupy, with tender rounds underneath a buttery cracker top.

Sharp cheddar brings a savory edge to the mild squash, while sour cream makes the filling rich without hiding the vegetables. The beaten eggs help it set as it bakes, so each serving holds together after a short rest. I like how the golden topping gives way to a soft, creamy center in every spoonful.

Why the Eggs Matter More Than the Cheese in a Squash Casserole

Cheddar adds flavor and a little richness, but it isn’t what holds a slice of this casserole together. The eggs do that work as they bake, binding the sour cream and squash into a soft, set filling. That’s why I whisk the eggs into the sour cream before adding the cheese and vegetables: the eggs spread through the mixture instead of clumping around individual pieces of squash.

The sour cream also has a job beyond making the filling creamy. Its tang keeps the squash from tasting flat, and its thick texture gives the eggs a base to coat. Together, those ingredients make a filling that’s tender rather than rubbery. The goal isn’t a firm, dry slice; it’s a casserole that holds its shape on a spoon while staying moist inside. Give the center time to set in the oven, then let the dish rest before serving so the filling can settle into neat, creamy portions.

What Keeps the Squash, Sour Cream, and Cracker Topping in Balance

• Yellow squash — Choose squash that feels firm, with smooth, unblemished skin. Cutting it into even 1/4-inch slices helps the pieces cook at the same rate and stay recognizable in the finished casserole.
• Yellow onion — Finely chopped onion softens alongside the squash and seasons the filling throughout. Keep the pieces small so they turn tender in the same boiling time as the squash.
• Sour cream — Its tangy richness gives the filling its creamy character. Plain sour cream is the right fit here; flavored varieties would pull the casserole in a different direction.
• Eggs — Lightly beating them before mixing helps them blend evenly into the sour cream. They’re the ingredient that gives the baked filling its set, so they aren’t a good ingredient to leave out.
• Sharp cheddar — Sharp cheddar brings a more pronounced savory flavor than mild cheddar. A block grated just before mixing melts smoothly; pre-shredded cheddar also works when convenience matters.
• Buttery round crackers and unsalted butter — The crackers make the crisp, golden top, while melted butter helps the crumbs toast instead of staying dry. Any buttery round cracker in this style works; unsalted butter lets the measured salt in the filling stay in balance.

From Fork-Tender Squash to a Set, Golden Casserole

Boil the Squash Until It’s Fork-Tender

Heat the oven to 350°F and coat a 2-quart baking dish with nonstick cooking spray. Bring the water and 1 teaspoon of the kosher salt to a boil in a 5-quart pot. Add the sliced squash and finely chopped onion, then cook for 8 to 10 minutes, until a fork slips into the squash easily. Don’t leave the pot before the squash is tender; firm centers won’t soften evenly during the bake.

Drain the Vegetables Before Mixing

Drain the squash and onion well in a colander, then let them stand for 5 minutes. This gives excess water time to escape before the vegetables go into the creamy filling. Press gently to release remaining liquid without breaking the squash into small pieces. The slices should still be easy to recognize when you fold them into the bowl.

Build a Smooth, Even Filling

Whisk the sour cream and lightly beaten eggs together in a large bowl. Stir in the cheddar, remaining 1/2 teaspoon of kosher salt, and black pepper until the seasoning is spread through the mixture. Fold in the drained squash and onion rather than stirring briskly, which can break up the tender slices. Spread the filling in the prepared baking dish.

Top and Bake Until the Center Sets

Stir the crushed buttery round crackers with the melted butter, then scatter the mixture evenly over the filling. Bake for 30 to 35 minutes, until the topping is golden and the center is set and reaches 160°F. If the crumbs are browning before the center is ready, keep an eye on the dish as it finishes baking. Let the casserole rest for 10 minutes before serving so the filling settles and scoops cleanly.

Small Changes That Shift the Casserole’s Texture

Questions That Come Up Before This Squash Casserole Goes in the Oven

Southern Yellow Squash Casserole

Southern yellow squash casserole combines tender squash, onion, sour cream, eggs, and sharp cheddar in a 2-quart baking dish. A buttery crushed-cracker topping bakes until golden, with the center set at 160°F.

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Prep Time 15 minutes mins

Cook Time 45 minutes mins

Standing and resting 15 minutes mins

Total Time 1 hour hr 15 minutes mins

Servings: 6 servings

Course: Side Dish

Cuisine: Southern

Calories: 340

Ingredients Equipment Method Notes

Ingredients

  

For the filling

• 10 cup water
• 1.5 tsp kosher salt divided
• 2 lb yellow squash cut into 1/4-inch slices
• 0.5 yellow onion medium, finely chopped
• 1 cup sour cream
• 2 eggs large, lightly beaten
• 1 cup sharp cheddar cheese shredded
• 0.25 tsp black pepper
• 1 nonstick cooking spray for coating

For the topping

• 1 cup buttery round crackers crushed (about 20 crackers)
• 3 tbsp unsalted butter melted

Equipment

• 1 2-quart baking dish
• 1 5-quart pot

Method

 

Prepare the squash

1. Preheat the oven to 350°F.
2. Coat a 2-quart baking dish with nonstick cooking spray.
3. Bring the water and 1 teaspoon of the salt to a boil in a 5-quart pot.
4. Add the squash and onion and cook for 8 to 10 minutes, until the squash is fork-tender.
5. Drain the squash and onion well in a colander.
6. Let them stand for 5 minutes, gently pressing out excess liquid.

Make the filling

1. Whisk the sour cream and eggs in a large bowl.
2. Stir in the cheddar, remaining 1/2 teaspoon salt, and pepper.
3. Fold the drained squash and onion into the sour cream mixture.
4. Spread the mixture in the prepared baking dish.

Top and bake

1. Stir the crushed crackers with the melted butter.
2. Scatter the mixture evenly over the casserole.
3. Bake for 30 to 35 minutes, until the topping is golden, the center is set, and the center reaches 160°F.
4. Rest for 10 minutes before serving.

Notes

Press excess liquid gently from the squash to help the casserole set. Refrigerate leftovers for 3 to 4 days; freezing is not recommended because it can affect the texture. For a lighter swap, use plain Greek yogurt in place of the sour cream.