Southern Squash Casserole

The cracker topping is the first thing I notice when this comes out of the oven: golden at the edges, buttery, and just crisp enough to contrast with the soft squash underneath. Southern squash casserole has a creamy, tender middle without turning into a pan of mush, and the sharp cheddar gives it a savory edge that keeps each bite from tasting flat.

I cook the squash and onion on the stove before they go into the baking dish. That gives the squash time to soften, while the sour cream, eggs, and cheese come together into a filling that holds its shape after baking. The topping is simple crushed buttery crackers tossed with melted butter; spread it evenly and it turns into a crisp lid over the casserole.

Why the Squash Needs a Colander Before It Meets the Filling

Yellow summer squash holds a surprising amount of water. It releases that liquid as it cooks, and any extra left clinging to the slices can thin out the sour cream and egg mixture. The casserole may still brown on top, but the middle can come out loose instead of creamy enough to scoop.

After cooking, transfer the squash and onion to a colander and let them drain for five minutes. Press gently; you’re trying to release pooled liquid, not mash the squash into a puree. This short pause also gives you a chance to see how much moisture has collected beneath the vegetables. Keep the slices intact as much as you can, and the finished filling will have soft pieces of squash rather than a uniform paste.

It’s worth treating this as part of the cooking, not an optional cleanup step. The squash is meant to be tender and moist, but the filling should set around it. A little care here makes the difference between a casserole you can portion neatly and one that runs across the plate.

What the Squash, Sour Cream, and Crackers Each Bring

• Yellow summer squash — It becomes soft and mild as it cooks, giving the casserole its tender vegetable base. Choose firm squash without soft spots; there’s no need to seek out a specialty variety. Slice it evenly so the pieces cook at about the same pace. Zucchini works in the same weight if that’s what you have, though the flavor is a little less sweet.
• Yellow onion — Finely chopped onion cooks alongside the squash and gives the mild vegetables a savory backbone. A regular grocery-store yellow onion is all you need; the useful detail is cutting it small enough to soften in the same cooking time.
• Sour cream and eggs — Sour cream makes the filling tangy and creamy, while the eggs help it hold together after baking. Use fresh eggs and a sour cream you enjoy eating; there’s no need for a premium brand. Plain Greek yogurt can stand in for the sour cream in the same quantity, but it makes the filling tangier and a little thicker.
• Sharp cheddar — Sharp cheddar gives the mild squash a stronger, savory cheese flavor. Freshly shredded cheese melts smoothly, but packaged shredded cheddar is convenient and works here, too. For a milder casserole, swap in mild cheddar in the same quantity.
• Buttery round crackers and butter — Crushed crackers make the topping crisp and give it a buttery, toasty flavor. A store-brand cracker is fine; crush it into small crumbs rather than leaving large pieces that won’t coat evenly. The melted butter helps the crumbs brown across the top.

Cooking the Squash Before Building the Casserole

Soften the Squash and Onion in the Dutch Oven

Heat the oven to 350°F and coat a 9×13-inch baking dish with nonstick cooking spray. Melt two tablespoons of butter in a 6-quart Dutch oven over medium heat, then add the sliced squash and finely chopped onion. Cover and cook for 10–12 minutes, stirring occasionally, until the squash is very tender. If a slice still feels firm when you press it with a spoon, give the mixture another moment on the heat.

Drain, Press Gently, and Cool

Move the cooked squash and onion to a colander and let them drain for five minutes. Press gently to release excess liquid without crushing the vegetables. Let the mixture cool for 10 minutes before you combine it with the eggs. It should feel warm rather than piping hot when you fold it into the bowl.

Mix the Creamy Cheddar Filling

Whisk the sour cream and eggs together in a large bowl until smooth, then stir in the shredded cheddar, salt, and black pepper. Fold in the cooled squash mixture with a broad spoon so the pieces stay recognizable. Scrape along the bottom of the bowl as you fold; that catches any sour cream or cheese that hasn’t been distributed yet. Stop once the squash is coated evenly.

Butter the Crumbs and Bake Until Set

Melt the remaining butter and toss it with the crushed crackers until the crumbs are evenly coated. Spread the squash mixture in the prepared baking dish, then scatter the topping across the surface. Bake for 30–35 minutes, until the topping is golden and the center reaches 160°F. Let the casserole rest for 10 minutes before serving so the filling has time to settle.

Three Simple Ways to Adapt This Squash Casserole

Questions That Come Up While Making Squash Casserole

Southern Squash Casserole

Southern squash casserole combines tender yellow summer squash and onion with a creamy cheddar filling under a golden buttery cracker topping. Bake it in a 9x13-inch dish until the center reaches 160°F, then rest before serving.

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Prep Time 20 minutes mins

Cook Time 47 minutes mins

Cooling and resting 20 minutes mins

Total Time 1 hour hr 27 minutes mins

Servings: 8 servings

Course: Side Dish

Cuisine: Southern

Calories: 330

Ingredients Equipment Method Notes

Ingredients

  

For the casserole

• 1 nonstick cooking spray for the baking dish
• 2.5 lb yellow summer squash sliced 1/4 inch thick
• 1 yellow onion medium, finely chopped
• 5 tbsp unsalted butter divided
• 1 cup sour cream
• 2 eggs large
• 1.5 cup sharp cheddar cheese shredded
• 0.75 tsp salt
• 0.25 tsp black pepper

For the topping

• 1 cup buttery round crackers crushed

Equipment

• 1 9x13-inch baking dish
• 1 6-quart Dutch oven

Method

 

Prepare and cook the squash

1. Preheat the oven to 350°F.
2. Coat a 9x13-inch baking dish with nonstick cooking spray.
3. Melt 2 tablespoons of the butter in a 6-quart Dutch oven over medium heat.
4. Add the squash and onion.
5. Cover and cook for 10–12 minutes, stirring occasionally, until the squash is very tender.
6. Transfer the squash mixture to a colander and drain for 5 minutes, gently pressing out excess liquid.
7. Let the squash mixture cool for 10 minutes.

Mix the filling

1. In a large bowl, whisk together the sour cream and eggs.
2. Stir in the cheddar, salt, and pepper.
3. Fold the cooled squash mixture into the sour cream mixture.

Make the topping

1. Melt the remaining 3 tablespoons butter.
2. Toss the cracker crumbs with the melted butter until evenly coated.

Assemble and bake

1. Spread the squash mixture in the prepared dish.
2. Sprinkle the cracker topping evenly over it.
3. Bake for 30–35 minutes, until the topping is golden and the center reaches 160°F.
4. Rest the casserole for 10 minutes before serving.

Notes

Drain the squash well and gently press out excess liquid to help the casserole set. Refrigerate leftovers for up to 3 days; freezing is not recommended because the creamy filling may change texture. For a gluten-free variation, use gluten-free buttery crackers.