Easy Baked Zucchini and Squash Casserole With Buttery Cracker Topping

A creamy, crowd-pleasing weeknight side with a crispy buttery cracker crown—30 minutes of prep, big summer flavor, and zero stress.

You want a side dish that makes veggies vanish from plates like magic? This is it. Tender zucchini and yellow squash, creamy sauce, and a buttery cracker crust that crackles when your fork hits it. It’s the kind of recipe that turns “Ugh, squash” into “Who took the last scoop?” with suspicious speed. No culinary school, no fuss—just smart technique and the kind of flavors that taste like you got help from your grandma and your favorite diner cook. Make it tonight and watch your table go quiet for all the right reasons.

What Makes This Special

This casserole nails the sweet spot between cozy and fresh. You get peak summer produce dressed in a velvety sauce, topped with a golden, salty-crunchy layer that feels like a warm hug. And yes, the buttery cracker topping is exactly as outrageous as it sounds—crisp, savory, and wildly addictive.

• Balanced texture: Creamy base + crispy topper = can’t-stop-eating territory.
• Weeknight-friendly: About 30 minutes of hands-on time and the oven does the rest.
• Reliable results: Techniques that keep squash from turning watery or mushy. (We like our crunch where it belongs.)
• Budget-savvy: Garden veggies, everyday dairy, and a sleeve of crackers. Big flavor, little spend.
• Flexible: Add protein, swap cheeses, go gluten-free—this recipe doesn’t throw a tantrum.

Ingredients Breakdown

• 2 medium zucchini, thinly sliced into 1/4-inch rounds (about 1 to 1 1/4 lb)
• 2 medium yellow squash, thinly sliced into 1/4-inch rounds (about 1 to 1 1/4 lb)
• 1 small yellow onion, thinly sliced
• 2 cloves garlic, minced
• 2 tablespoons olive oil (for sautéing)
• 1 teaspoon kosher salt, divided
• 1/2 teaspoon black pepper
• 1 teaspoon Italian seasoning (or 1/2 teaspoon dried thyme + 1/2 teaspoon dried oregano)
• 1 cup shredded sharp cheddar
• 1/2 cup grated Parmesan, divided (1/4 cup for filling, 1/4 cup for topping)
• 1/2 cup sour cream or plain Greek yogurt
• 1 large egg, lightly beaten
• 1 tablespoon Dijon mustard (optional but excellent flavor boost)
• 1 tablespoon chopped fresh parsley or chives
• 1 sleeve buttery round crackers (about 30 crackers; ~1 1/2 cups crushed)
• 4 tablespoons unsalted butter, melted
• 1/4 teaspoon smoked paprika (optional; adds subtle depth)
• Pinch red pepper flakes (optional; gentle heat)
• Nonstick spray or butter for greasing the dish

Yield: 6–8 servings as a side. Active time: ~30 minutes. Total time: ~55–65 minutes plus a 10-minute rest.

Let’s Get Cooking – Instructions

1. Heat the oven: Preheat to 375°F (190°C). Grease a 2-quart baking dish (or 9×13-inch for a thinner casserole) with butter or spray.
2. De-water the squash (key step): Toss zucchini and yellow squash with 1/2 teaspoon salt and let sit in a colander for 10–15 minutes. Pat dry thoroughly with paper towels. This keeps your casserole from getting soggy.
3. Sauté aromatics: Heat 2 tablespoons olive oil in a large skillet over medium. Add onion and cook until translucent and lightly golden, about 5–7 minutes. Stir in garlic for 30 seconds. Remove from heat.
4. Make the creamy base: In a large bowl, combine the sautéed onion/garlic, 1/2 teaspoon salt (remaining), 1/2 teaspoon black pepper, 1 teaspoon Italian seasoning, 1 cup cheddar, 1/4 cup Parmesan, 1/2 cup sour cream, 1 egg, and 1 tablespoon Dijon if using. Fold in the dried squash and 1 tablespoon chopped herbs.
5. Assemble: Spread mixture evenly in the prepared dish. Press gently to create a flat surface for the topping. Cover with foil.
6. First bake: Bake covered for 20 minutes to set the base and steam the squash slightly.
7. Make the cracker topping: While it bakes, crush 1 sleeve buttery crackers into coarse crumbs. Stir with 4 tablespoons melted butter, remaining 1/4 cup Parmesan, and 1/4 teaspoon smoked paprika if desired.
8. Top and finish: Remove foil. Sprinkle the buttery crumbs evenly over the casserole. Bake uncovered for 15–20 minutes, until the topping is crispy and the edges are bubbling.
9. Optional boost: For extra crunch, broil on high for 1–2 minutes. Watch closely; it goes from golden to “oops” quickly.
10. Rest and serve: Let the casserole rest for 10 minutes to set. Garnish with extra herbs. Serve warm and prepare to deflect compliments.

Storage Tips

Leftovers keep well, and the flavor deepens by day two—like yesterday’s pizza, but classy. Cool completely, then cover and refrigerate for 3–4 days. Reheat at 350°F for 15–20 minutes until hot; tent with foil if the topping is browning too fast.

Want to freeze? You can, but the cracker topping softens. For best results, freeze without the topping. Bake the base, cool, wrap tightly, and freeze for up to 2 months. Reheat from thawed at 350°F until warm, then add fresh cracker topping and bake another 10–15 minutes.

Quick single-serving reheat: Pop a square in the air fryer at 325°F for 6–8 minutes. FYI, this rescues the crunch like a champ.

Health Benefits

Yes, there’s buttery topping, and yes, there’s balance. Zucchini and yellow squash are naturally low in calories and high in water, helping with hydration and fullness. They bring fiber, vitamin C, and antioxidants like lutein and zeaxanthin—great for eyes and skin.

Using Greek yogurt instead of sour cream adds a bump of protein and a tangy lift. Cheddar and Parmesan provide calcium, and because this casserole is rich, you can enjoy a moderate portion and still feel satisfied. IMO, when veggies taste this good, you’ll eat more of them—win.

Common Mistakes to Avoid

• Skipping the salting step: That 10-minute wait prevents a watery, soupy casserole. Don’t skip it.
• Thick slices: Cut squash to 1/4-inch for even cooking. Too thick = crunchy in a bad way.
• Overbaking the base: The first bake sets the filling; the second bake is for browning. Don’t turn it into veggie confetti.
• Soggy topping: Add cracker crumbs only for the second bake and keep the final rest short. Steam is the enemy of crisp.
• Underseasoning: Squash is mild. Use the salt, pepper, and herbs as written. Taste the base before baking if you’re nervous.
• Wrong pan size: Too deep and the center won’t set; too shallow and it overdries. A 2-quart dish is the sweet spot.
• Skipping the rest: Those 10 minutes help the casserole slice cleanly. Your patience will be rewarded.

Recipe Variations

• Gluten-free: Use gluten-free buttery crackers or mix 1 cup GF panko with 2 tablespoons almond flour and butter.
• Keto-ish: Swap crackers for crushed pork rinds mixed with Parmesan and butter. Shockingly good crunch.
• Protein boost: Fold in 2 cups shredded rotisserie chicken or 8 ounces cooked Italian sausage before baking.
• Tex-Mex twist: Use Pepper Jack, add 1/2 teaspoon cumin, and dot with chopped pickled jalapeños. Serve with salsa.
• Mediterranean mood: Swap cheddar for feta, add kalamata olives, and finish with lemon zest.
• Mushroom umami: Sauté 8 ounces sliced mushrooms with the onions. Add a splash of soy or Worcestershire.
• Tomato topper: Layer thin tomato slices under the crackers. Sprinkle with extra oregano for pizza vibes.
• Individual portions: Divide into muffin tins or ramekins. Bake times shorten to 12–15 minutes covered + 8–10 minutes uncovered.

FAQ

Can I make this casserole ahead of time?

Yes. Assemble the base up to the first bake, cover, and refrigerate for up to 24 hours. When ready to serve, bake the base for 20 minutes, add the cracker topping, and finish baking until golden. You can also fully bake without the topping, chill, then add fresh crumbs and reheat for a just-made crunch.

How do I keep the casserole from getting watery?

Two moves: salt and drain the squash for 10–15 minutes, then pat dry, and avoid overbaking. The egg and dairy bind the moisture into a creamy sauce, but excess water from undrained squash will dilute it. Also, don’t cover the pan during the second bake—steam is the enemy of crisp.

What cheeses work best besides cheddar?

Sharp cheddar is classic, but Gruyère, fontina, or a mozzarella-Parmesan blend melt beautifully. If you want big flavor, go half cheddar, half fontina. Parmesan in the topping adds savory depth you’ll miss if it’s gone, so keep that in the mix.

Can I skip the egg?

Yes, but expect a looser texture. For an egg-free option, use 3 tablespoons cream cheese or 1 tablespoon cornstarch whisked into the sour cream/yogurt. It won’t slice as cleanly, but it will still taste fantastic.

How do I reheat without losing the crunchy topping?

Use dry heat. Reheat in a 350°F oven for 15–20 minutes or in an air fryer at 325°F for 6–8 minutes. Avoid microwaves unless you like cracker gum. If the bottom is hot but the top needs help, broil for 60 seconds at the end.

Can I use frozen squash?

You can, but thaw completely and press out as much water as humanly possible. Toss with a bit of cornstarch (1 teaspoon) to help absorb extra moisture. Fresh squash delivers better texture, so use that when it’s in season, FYI.

What size baking dish should I use?

A 2-quart casserole dish is ideal. A 9×13-inch pan also works for a thinner layer and extra crisp topping. If the dish is too deep, the center may not set; too large and it can dry out. Adjust bake times by a few minutes either way.

Is this kid-friendly?

Absolutely. The creamy sauce and cracker topping are kid kryptonite in the best way. If you’re cooking for picky eaters, peel the squash for a smoother bite and stick with cheddar. Add a sprinkle of sweet paprika for color without heat.

My Take

This is the side dish I pull out when I need a guaranteed win. It respects the squash—keeps it tender, not limp—and then throws a party on top with buttery crumbs that shatter just enough. It’s humble in cost, generous in flavor, and plays nice with almost any main. The trick is simple: control moisture, season with intent, and never skimp on the crunch. Make it once and it’ll be your “bring the good dish” recipe from here on out—no sales pitch required.