Make yellow squash casserole with fresh summer squash, cheese, and a crisp cracker topping for a hearty baked side everyone will dig into!

This yellow squash casserole is exactly what I want when a basket of fresh summer squash is sitting on my counter and I want to turn it into something far more tempting than another pile of sautéed vegetables.

Ingredients

For Squash Filling

• 2 1/2 pounds yellow summer squash, about 6 medium squash, sliced into 1/4-inch rounds
• 1 medium sweet onion, about 1 cup thinly sliced or finely chopped
• 2 tablespoons unsalted butter
• 1 teaspoon kosher salt, divided
• 1/2 teaspoon freshly ground black pepper
• 1/2 teaspoon garlic powder
• 2 large eggs
• 1/2 cup full-fat sour cream
• 1 cup freshly shredded sharp cheddar cheese
• 1/4 cup finely grated Parmesan cheese
• 1 teaspoon Dijon mustard
• 1 tablespoon chopped fresh chives or parsley, optional

For Buttery Cracker Topping

• 1 cup coarsely crushed buttery round crackers, about 24 to 28 crackers
• 3 tablespoons unsalted butter, melted
• 1/4 cup freshly shredded sharp cheddar cheese
• 2 tablespoons finely grated Parmesan cheese

Servings: 8

How to Make Yellow Squash Casserole

Heat oven to 375°F and lightly butter or grease a 2-quart baking dish or an 8 x 11-inch casserole dish. I like to prepare my baking dish before I touch squash because once filling is mixed, I want to get it into oven rather than leave it sitting around and releasing more liquid.

Slice yellow squash into rounds about 1/4 inch thick. Try to keep slices fairly even, but you absolutely do not need to measure each piece as though squash has entered a geometry competition.

If some squash are especially wide, cut those rounds in half so everything cooks at roughly same pace.

Melt 2 tablespoons butter in a large, wide skillet over medium-high heat, then add squash, onion, and 1/2 teaspoon salt. A wide skillet matters here because you want moisture to evaporate rather than trap squash in a deep pan where it starts steaming.

Cook for about 8 to 10 minutes, stirring every minute or so, until squash looks glossy, has softened around edges, and can be pierced with a fork but still offers a tiny bit of resistance in center.

Do not cook it until completely limp. Squash will spend another half hour in oven, and starting with slightly firm slices gives finished casserole much better texture!

As squash cooks, you will notice liquid collecting in pan. That is exactly what we are trying to remove now instead of discovering it underneath casserole later.

Transfer cooked squash and onion into a colander set over sink and let everything drain for 5 to 10 minutes. Give colander one or two gentle shakes, but do not mash squash or press it aggressively.

I sometimes leave it draining while I mix filling, which is just enough time for steam and excess moisture to escape.

In a large mixing bowl, whisk 2 eggs, 1/2 cup sour cream, Dijon mustard, remaining 1/2 teaspoon salt, black pepper, and garlic powder until smooth.

Stir in 1 cup sharp cheddar, 1/4 cup Parmesan, and fresh herbs if using. Filling should look thick and creamy rather than pourable. If it seems quite loose, resist temptation to add milk.

Squash will release a little more moisture in oven, so a thick mixture is exactly what you want at this stage.

Add drained squash and onion to cheese mixture and fold everything together gently with a large spoon or silicone spatula. I prefer folding rather than vigorous stirring because squash is already tender, and keeping some slices intact gives casserole a much nicer texture.

Make sure creamy mixture reaches all through squash instead of remaining in one cheesy pocket at bottom of bowl.

Taste is harder to adjust once raw egg has been added, so if you are nervous about seasoning, taste one piece of cooked squash before adding it to egg mixture and add another small pinch of salt if needed.

Spoon mixture into prepared baking dish and spread it into an even layer without pressing it down too firmly. A little unevenness on top is actually useful because those raised areas catch crumbs and brown beautifully!

Put crushed crackers in a small bowl, pour over 3 tablespoons melted butter, and stir until crumbs look evenly moistened.

Add 1/4 cup cheddar and 2 tablespoons Parmesan, toss again, then scatter topping loosely across casserole.

Do not pack crumbs down. Loose crumbs have more exposed edges, and exposed edges are where all that golden, buttery crunch happens.

Bake casserole uncovered at 375°F for 25 to 30 minutes. Around 22-minute mark, start watching it rather than trusting timer blindly. You are looking for bubbling around edges, a center that looks set rather than wet, and a cracker topping that has turned golden brown.

If filling is bubbling nicely but crumbs still look pale, give casserole another 2 or 3 minutes. If topping is browning too quickly, loosely place a piece of foil over top for remaining baking time.

Remove casserole from oven and, difficult as it may be when your kitchen smells like butter and toasted cheese, let it rest for 10 minutes before serving.

Do not skip this step!

Resting allows hot filling to settle and thicken, so your first scoop comes out creamy and spoonable instead of spreading across plate. It also keeps you from scorching your tongue on molten cheddar, which is not exactly how dinner needs to begin.

Serving Suggestions

Yellow squash casserole works beautifully beside simple roasted, grilled, or slow-cooked meats because its creamy filling and crisp topping bring plenty of flavor without needing a complicated main dish.

Serve it with:

• Roast chicken or rotisserie chicken
• Grilled chicken breasts
• Baked ham
• Pork tenderloin
• Grilled pork chops
• Meatloaf
• Barbecue chicken
• Roast turkey
• Grilled steak
• Pulled pork
• Baked salmon
• A simple green salad and crusty bread for a lighter meal

For a holiday meal, it fits especially well alongside turkey, ham, mashed potatoes, green beans, and dinner rolls. For an everyday dinner, I like it with grilled chicken and sliced tomatoes because casserole already brings enough richness to plate.

If you have fresh summer squash waiting in your kitchen, this yellow squash casserole is a very good reason to turn on oven! 

Hungry for more feel-good meals? Explore these 21 Anti-Inflammatory Breakfast Recipes for a nourishing start and 10 Anti-Inflammatory Dinner Recipes for delicious evenings that make healthy eating easy!