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Baked squash and zucchini casserole with a golden cheesy Parmesan crust

Squash and Zucchini Casserole with Parmesan Crumb

Roasted yellow squash and zucchini baked in a Greek yogurt and white cheddar custard under a crispy Parmesan panko topping.
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Prep Time 20 minutes
Cook Time 45 minutes
Resting 10 minutes
Total Time 1 hour 15 minutes
Servings: 8 servings
Course: Side Dish
Cuisine: American
Calories: 210
Ingredients Method Notes

Ingredients
  

Filling
  • 1 lb yellow squash sliced 1/4 inch thick
  • 1 lb zucchini sliced 1/4 inch thick
  • 1 small onion thinly sliced
  • 2 tbsp olive oil
  • 1/2 tsp salt
  • 2 large eggs
  • 1/2 cup plain Greek yogurt whole or 2%
  • 2 cloves garlic minced
  • 1 tsp fresh thyme leaves or 1/2 tsp dried
  • 1/2 tsp black pepper
  • 1 cup white cheddar or Gruyère shredded
  • 1/4 cup Parmesan finely grated
Parmesan crumb
  • 3/4 cup panko breadcrumbs
  • 1/4 cup Parmesan finely grated
  • 1 tbsp butter melted, or olive oil
  • 2 tbsp fresh parsley chopped

Method
 

  1. Preheat the oven to 425°F (220°C). Slice the squash and zucchini into 1/4-inch rounds and thinly slice the onion.
  2. Toss the vegetables with olive oil and salt, spread on two baking sheets and roast 15–18 minutes until tender with golden edges. Reduce the oven to 375°F (190°C).
  3. Whisk the eggs, yogurt, garlic, thyme and pepper. Stir in the cheddar and 1/4 cup Parmesan.
  4. Cool the vegetables 5 minutes, fold into the custard and spread in a greased 2-quart baking dish.
  5. Mix the panko, remaining Parmesan and melted butter and sprinkle over the top.
  6. Bake 25–30 minutes until set and golden. Rest 10 minutes and garnish with parsley.

Notes

Roast the vegetables up to 2 days ahead. Leftovers keep 4 days refrigerated; reheat in the oven or air fryer to re-crisp the topping. Nutrition is an estimate.