That buttery cracker topping. Golden, crunchy, the kind that makes everyone go quiet for a second when their fork hits it.
Underneath: a creamy, cheesy, just-spicy-enough bed of tender yellow squash and sweet onion. Mayo and sour cream doing their quiet tangy thing in the background. Sharp cheddar. A whisper of fresh thyme. It’s comfort food that doesn’t need to TRY that hard (you know?).
Bake it for 30 minutes and you’ve got the potluck dish people REQUEST. Summer squash abundance? Officially solved.
How to Prevent a Watery Casserole
Squash holds a ton of water, so fight back or you will be serving soup…. here is how.
- Salt the raw slices for 15 minutes, then SQUEEZE OUT the liquid with your hands before cooking.
- Cook UNCOVERED so the steam actually escapes instead of pooling back in.
- Drain any liquid sitting in the bowl after the rest step (do not skip it!).
- FULL-FAT mayo and sour cream only… low-fat versions break and weep into the filling.
How to Get a Golden, Crunchy Topping
Crush crackers into coarse crumbs, not fine dust. (Texture matters! You want some bite.) Toss with TWO tablespoons of melted butter until every piece glistens.
Spread the buttered crumbs EVENLY across the casserole right before baking. Press down gently so they anchor to the filling below. No dumping in the center and hoping for the best.
Bake at 375°F for 30 minutes until deep golden brown. Pale looking? Run it under the broiler for 60 to 90 seconds. WATCH CLOSELY because crackers go from golden to burnt FAST.
Rest for 5 to 10 minutes before serving. This firms up the topping and prevents trapped steam from creating sogginess. Serve hot for maximum crunch!
What to Serve with Yellow Squash Casserole
Pair this casserole with dishes that won’t fight its creamy, cheesy vibe. Here are solid options!
- Roasted or grilled chicken (simple seasoning lets the casserole shine)
- Pork chops or meatloaf for a classic Southern plate
- Green beans, sautéed kale, or a crisp garden salad to cut the richness
- Cornbread or crusty bread for soaking up every bite
- BBQ ribs or pulled pork if you’re going full backyard spread
Storage & Reheating Tips
Fridge those leftovers in an AIRTIGHT container for up to 3 days. Skip the freezer (the mayo base gets weird and grainy upon thawing, just don’t).
Reheat at 350°F for 15 minutes, covered with foil so the cracker topping doesn’t scorch. Microwave works in 2-3 minutes on medium… but you’ll sacrifice that CRUNCH.
Recipes Like This One
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- Easy Yellow Squash Casserole with Stuffing
- Hot Chicken Salad Casserole with Potato Chips
- Easy Yellow Squash Dressing
- BBQ Ranch Chicken Casserole
- Crockpot Tuna Casserole
Estimated Nutrition
Estimated nutrition for the whole recipe (without optional ingredients):
- Calories: 970-1100
- Protein: 22-27 g
- Fat: 68-78 g
- Carbohydrates: 75-90 g
Ingredients
For the squash mixture:
- 3 lb yellow squash (cut into 1/2-inch thick slices)
- 1 onion (finely diced into 1/4-inch pieces)
- 3/4 tsp salt
- 1 1/2 tsp onion powder
- 1 1/2 tsp garlic powder
- 1/2 tsp black pepper
- 1/2 tsp cayenne pepper
- 1/3 cup mayonnaise
- 1/3 cup sour cream
- 1 1/4 cups sharp cheddar cheese
- 1/2 tsp fresh thyme leaves
For the topping:
- 20 crackers (crushed into small, coarse crumbs)
- 2 tbsp unsalted butter, melted
Step 1: Prep Veggies and Spices
- 3 lb yellow squash, sliced into 1/2-inch thick rounds
- 1 onion, finely diced
- 3/4 tsp salt
- 1 1/2 tsp onion powder
- 1 1/2 tsp garlic powder
- 1/2 tsp black pepper
- 1/2 tsp cayenne pepper
- 20 crackers, crushed into coarse crumbs
Slice the yellow squash into 1/2-inch thick rounds and finely dice the onion into 1/4-inch pieces.
In a small bowl, combine the salt, onion powder, garlic powder, black pepper, and cayenne pepper—mixing them together ensures even seasoning distribution throughout the dish.
Crush the crackers into small, coarse crumbs (you want some texture, not fine breadcrumbs) and set aside.
I like to do all my prep work first so I can focus on the cooking without interruption.
Step 2: Sauté Until Tender
- 3 lb yellow squash, sliced
- 1 onion, finely diced
- spice mixture from Step 1
Heat a large skillet over medium-high heat and add the sliced squash and diced onion.
Sprinkle with the spice mixture from Step 1 and cook for 10 minutes, stirring occasionally, until the squash is tender and begins to release its moisture.
The squash will soften and the onion will become translucent as it cooks.
Transfer the cooked mixture to a bowl and let it cool for 5-10 minutes so it’s manageable to work with.
Step 3: Combine the Cheese Mixture
- cooked squash mixture from Step 2
- 1/3 cup mayonnaise
- 1/3 cup sour cream
- 1 1/4 cups sharp cheddar cheese
- 1/2 tsp fresh thyme leaves
Once the squash mixture has cooled slightly, stir in the mayonnaise, sour cream, and sharp cheddar cheese until everything is evenly combined.
Gently fold in the fresh thyme leaves, which will add a subtle herbaceous note to balance the richness.
I find that stirring in the creamy ingredients while the squash is still warm helps them distribute more smoothly and creates a cohesive sauce.
Step 4: Layer and Add Crumbs
- squash and cheese mixture from Step 3
- buttered cracker crumbs
Preheat your oven to 375°F.
Grease a 9×13 inch baking dish lightly with butter or cooking spray, then transfer the squash mixture into the prepared dish and spread it evenly.
Toss the crushed crackers from Step 1 with the melted butter until they’re lightly coated, then sprinkle them evenly over the top of the casserole.
The buttered crackers will toast and create a golden, crunchy crust.
Step 5: Bake and Let Cool
Place the casserole in the preheated 375°F oven and bake for 30 minutes, until the top is golden brown and the filling is hot throughout.
Remove from the oven and let it rest for 5-10 minutes before serving—this allows the casserole to set slightly and makes it easier to portion without falling apart.
Simple Yellow Squash Casserole with Mayonnaise
Ingredients
Method
- Slice the yellow squash into 1/2-inch thick rounds and finely dice the onion into 1/4-inch pieces. In a small bowl, combine the salt, onion powder, garlic powder, black pepper, and cayenne pepper—mixing them together ensures even seasoning distribution throughout the dish. Crush the crackers into small, coarse crumbs (you want some texture, not fine breadcrumbs) and set aside. I like to do all my prep work first so I can focus on the cooking without interruption.
- Heat a large skillet over medium-high heat and add the sliced squash and diced onion. Sprinkle with the spice mixture from Step 1 and cook for 10 minutes, stirring occasionally, until the squash is tender and begins to release its moisture. The squash will soften and the onion will become translucent as it cooks. Transfer the cooked mixture to a bowl and let it cool for 5-10 minutes so it's manageable to work with.
- Once the squash mixture has cooled slightly, stir in the mayonnaise, sour cream, and sharp cheddar cheese until everything is evenly combined. Gently fold in the fresh thyme leaves, which will add a subtle herbaceous note to balance the richness. I find that stirring in the creamy ingredients while the squash is still warm helps them distribute more smoothly and creates a cohesive sauce.
- Preheat your oven to 375°F. Grease a 9x13 inch baking dish lightly with butter or cooking spray, then transfer the squash mixture into the prepared dish and spread it evenly. Toss the crushed crackers from Step 1 with the melted butter until they're lightly coated, then sprinkle them evenly over the top of the casserole. The buttered crackers will toast and create a golden, crunchy crust.
- Place the casserole in the preheated 375°F oven and bake for 30 minutes, until the top is golden brown and the filling is hot throughout. Remove from the oven and let it rest for 5-10 minutes before serving—this allows the casserole to set slightly and makes it easier to portion without falling apart.