Yellow Squash and Zucchini Casserole

This Yellow Squash and Zucchini Casserole is one of my go-to vegetable sides because it’s creamy, flavorful, and so easy to make. The combination of tender yellow squash, zucchini, and a cheesy, savory mixture topped with a golden crust makes it a crowd-pleaser every time. Even picky eaters end up going back for seconds!

Ingredients

Vegetables

2 cups sliced yellow squash
2 cups sliced zucchini
1 small onion, thinly sliced
1 tablespoon olive oil
½ teaspoon salt
½ teaspoon black pepper

Casserole Base

½ cup sour cream or Greek yogurt
1 cup shredded cheddar or Monterey Jack cheese
2 large eggs, lightly beaten
1 teaspoon garlic powder
½ teaspoon dried thyme or Italian seasoning
¼ teaspoon paprika

Topping

½ cup Panko breadcrumbs
2 tablespoons grated Parmesan cheese
1 tablespoon melted butter

Instructions

Step 1: Prepare the Vegetables

Slice the squash and zucchini evenly.
Toss with olive oil, salt, pepper, and sliced onions.
Optionally, sauté or air fry for 5–8 minutes to reduce extra moisture.

Step 2: Make the Casserole Base

In a large bowl, combine sour cream, shredded cheese, eggs, garlic powder, thyme, and paprika.
Stir until smooth and creamy.

Step 3: Combine

Add the prepared vegetables to the cheese mixture.
Gently fold until all pieces are coated.

Step 4: Prepare the Topping

Mix Panko breadcrumbs, Parmesan, and melted butter in a small bowl.

Step 5: Assemble

Grease a 9×9-inch or similarly sized baking dish.
Pour in the vegetable mixture.
Sprinkle the breadcrumb mixture evenly on top.

Step 6: Bake

Bake at 350°F (175°C) for 25–30 minutes, or until the top is golden and the casserole is bubbling.
Let it rest for 5 minutes before serving.

@kelly.cockrell_

Tips for the Best Casserole

Slice vegetables evenly for uniform cooking.
Pre-cooking the squash and zucchini helps reduce excess liquid.
Use a mix of cheddar and Monterey Jack for extra flavor.
Let the casserole rest before slicing to hold its shape.
Add a pinch of nutmeg or smoked paprika for a subtle flavor boost.

Variations

Protein Boost: Add cooked chicken, bacon, or sausage.
Cheesy Twist: Mix in mozzarella or Gruyère cheese.
Low-Carb Option: Use almond flour or crushed pork rinds for topping.
Extra Veggies: Include mushrooms, bell peppers, or spinach.
Gluten-Free: Use gluten-free breadcrumbs or omit topping.

Serving Suggestions

Serve alongside grilled or roasted meats.
Pair with rice or quinoa for a complete meal.
Top with fresh herbs like parsley or chives for garnish.
Serve warm with a dollop of sour cream for extra creaminess.

Storage and Reheating

Refrigerator: Store in an airtight container for 3–4 days.
Freezer: Freeze portions for up to 2 months (best without topping).
Reheat: Microwave or bake at 325°F for 5–7 minutes until warmed through.

FAQs

Can I make this ahead of time?

Yes. Prepare the casserole, cover, and refrigerate for up to 24 hours before baking. Add the topping right before baking.

How do I prevent watery casserole?

Pre-cook or sauté the squash and zucchini slightly to remove excess moisture.

Can I make this dairy-free?

Yes. Use dairy-free cheese and yogurt alternatives, and replace butter with olive oil for the topping.

Can I use only squash or only zucchini?

Yes, either works fine. Using both gives the best texture and flavor.

Can I make this in an air fryer?

Yes, use an air fryer-safe dish and cook at 350°F for 15–20 minutes until bubbly and golden.

This Yellow Squash and Zucchini Casserole is creamy, cheesy, and full of flavor while still being simple to make. It’s perfect for family dinners, potlucks, or holiday gatherings. Every bite balances soft vegetables with a golden, crunchy top, making it a dish you’ll want to make again and again.