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Easy Squash and Zucchini Casserole Recipe with Cheddar and Crispy Breadcrumbs

Easy Squash and Zucchini Casserole Recipe

Sliced zucchini and yellow squash are sautéed with onion and garlic, covered with sharp cheddar, and finished with a crisp Parmesan breadcrumb topping. This colorful casserole makes 6 servings and takes about 45–50 minutes from start to finish.
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Prep Time 15 minutes
Cook Time 25 minutes
Total Time 45 minutes
Servings: 6 servings
Ingredients Method Notes

Ingredients
  

Vegetables
  • 2 medium Medium zucchini, sliced 1/4-inch thick
  • 2 medium Medium yellow squash, sliced 1/4-inch thick
  • 1 small Small yellow onion, thinly sliced or chopped
Seasoning and Cooking
  • 2 tablespoons Butter or olive oil
  • 2 cloves Garlic, minced
  • 1/2 teaspoon Kosher salt, plus more for salting vegetables
  • 1/4 teaspoon Black pepper
Cheese and Topping
  • 1 cup Shredded sharp cheddar cheese
  • 1/2 cup Panko breadcrumbs or seasoned breadcrumbs
  • 2 tablespoons Grated Parmesan cheese
  • 1 tablespoon Melted butter or olive oil for topping

Method
 

Step-by-Step
  1. Heat the oven to 375°F and lightly grease a 9-inch square or similarly sized casserole dish.
  2. Slice the zucchini and yellow squash into even 1/4-inch rounds. Lightly salt the slices, let them stand for 10 minutes, and pat them dry with paper towels.
  3. Heat 2 tablespoons butter or olive oil in a large skillet over medium heat. Cook the onion for 3–4 minutes, until it begins to soften.
  4. Add the garlic, zucchini, and yellow squash. Season with the pepper and remaining salt, then sauté for 5–7 minutes, stirring occasionally, until the vegetables are slightly tender but not soft.
  5. Transfer the vegetables to the prepared casserole dish and sprinkle the cheddar evenly over the top.
  6. Combine the breadcrumbs, Parmesan, and 1 tablespoon melted butter or oil. Sprinkle the topping evenly over the cheese.
  7. Bake uncovered for 25–30 minutes, until bubbling and golden. Rest for 5 minutes before serving.

Notes

Salting and drying the squash helps prevent a watery casserole. Slice evenly and sauté briefly so the vegetables finish tender in the oven without becoming mushy. Store leftovers covered in the refrigerator and reheat until hot.