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Garden Zucchini Casserole

A creamy, cheesy baked zucchini casserole with herbs and a golden Parmesan top.
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Prep Time 20 minutes
Cook Time 40 minutes
Total Time 1 hour
Servings: 6 servings
Course: Main Course, Side Dish
Cuisine: American
Calories: 220
Ingredients Equipment Method Notes

Ingredients
  

Zucchini and aromatics
  • 4 medium zucchini sliced into thin half-moons or rounds
  • 1 small yellow onion finely chopped
  • 2 cloves garlic minced
  • 1 tablespoon olive oil
  • 1 pinch salt for drawing moisture from zucchini
Casserole mixture
  • 3 large eggs
  • 1 cup sour cream
  • 1 cup mozzarella cheese shredded
  • 1/4 cup Parmesan cheese grated
  • 1/2 cup breadcrumbs
  • 1 tablespoon fresh parsley chopped
  • 1 teaspoon fresh rosemary chopped, or 1/2 teaspoon dried rosemary
  • 3/4 teaspoon salt
  • 1/2 teaspoon black pepper
Topping and dish prep
  • 1/4 cup Parmesan cheese grated, for topping
  • 2 tablespoons butter for greasing the dish and dotting the top

Equipment

  • 1 9-inch square baking dish or similar 2-quart casserole dish
  • 1 Large mixing bowl
  • 1 skillet
  • 1 Colander
  • 1 cutting board
  • 1 knife
  • 1 whisk

Method
 

  1. Slice the zucchini into thin half-moons or rounds. Place in a colander, sprinkle lightly with salt, and let sit for 10 to 15 minutes to release excess moisture. Pat dry well.
  2. Preheat the oven to 375°F. Grease a 9-inch square baking dish with some of the butter.
  3. Heat the olive oil in a skillet over medium heat. Add the chopped onion and cook for 4 to 5 minutes until softened.
  4. Add the minced garlic to the skillet and cook for 30 seconds, just until fragrant. Remove from the heat.
  5. In a large bowl, whisk together the eggs and sour cream until smooth.
  6. Stir in the mozzarella, 1/4 cup Parmesan, breadcrumbs, parsley, rosemary, salt, and black pepper.
  7. Fold the drained zucchini and sautéed onion mixture into the bowl and stir until evenly combined.
  8. Transfer the mixture to the prepared baking dish and spread into an even layer.
  9. Sprinkle the remaining 1/4 cup Parmesan over the top and dot lightly with the remaining butter.
  10. Bake for 35 to 40 minutes, until the casserole is set in the center and the top is golden brown.
  11. If desired, broil for 1 to 2 minutes at the end for deeper color, watching closely.
  12. Let the casserole rest for 10 minutes before slicing and serving.

Notes

Salting and drying the zucchini helps prevent a watery casserole. Let the baked casserole rest before slicing for the best texture. Greek yogurt can replace sour cream, and mozzarella can be swapped with Monterey Jack or mild cheddar.