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A baked squash zucchini casserole with golden-brown topping

Creamy Zucchini and Yellow Squash Casserole

This creamy zucchini and yellow squash casserole is a comforting and easy-to-make side dish, perfect for any meal. Tender squash and zucchini are baked in a rich, cheesy sauce with a crispy Ritz cracker topping.
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Prep Time 20 minutes
Cook Time 35 minutes
Total Time 55 minutes
Servings 6 people
Calories 280 kcal

Equipment

  • Baking Dish (9x13 inch)
  • Skillet
  • Large Bowl
  • Whisk

Ingredients
  

Squash Mixture

  • 2 medium Yellow Squash thinly sliced
  • 2 medium Zucchini thinly sliced
  • 1/2 small Onion finely chopped

Sauce

  • 2 tablespoons Butter melted
  • 2 tablespoons All-Purpose Flour
  • 1 cup Milk whole or 2%
  • 2 large Eggs beaten
  • 1 cup Cheddar Cheese shredded (sharp or medium)
  • 1/4 cup Parmesan Cheese grated
  • 1/2 teaspoon Garlic Powder
  • 1/2 teaspoon Dried Thyme
  • 1/2 teaspoon Salt or to taste
  • 1/4 teaspoon Black Pepper or to taste

Topping

  • 1/2 cup Crushed Ritz Crackers

Instructions
 

Preparation

  • Preheat the oven to 375°F (190°C) and grease a 9x13 inch baking dish. Blot sliced squash and zucchini with paper towels to remove excess moisture.

Cooking

  • Melt 1 tablespoon of butter in a skillet over medium heat, then sauté the chopped onion until softened (3-4 minutes). Stir in garlic powder and dried thyme, cooking for 1 minute until fragrant.
  • Add the remaining 1 tablespoon of melted butter to the skillet, whisk in flour for 1 minute to create a roux, then gradually whisk in milk until smooth and thickened (2-3 minutes). Remove from heat.
  • In a large bowl, whisk beaten eggs, then slowly temper the hot milk mixture into the eggs by gradually adding it while whisking. Stir in cheddar cheese, Parmesan cheese, salt, and black pepper.
  • Combine the prepared squash, zucchini, and sautéed onions with the cheese sauce, tossing gently to ensure all vegetables are coated.

Baking

  • Pour the vegetable mixture into the prepared baking dish and spread evenly. Sprinkle crushed Ritz crackers over the top of the casserole.
  • Bake for 30-35 minutes, or until the casserole is bubbly, vegetables are tender, and the topping is golden brown. If needed, loosely tent with foil to prevent over-browning.

Serving

  • Remove from the oven and let rest for 5-10 minutes before serving.

Notes

For extra flavor, you can add a pinch of nutmeg to the cheese sauce. This casserole reheats well, making it a great option for meal prep.