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Vegetable Breakfast Casserole with Hash Brown Crust

Vegetable breakfast casserole with hash brown crust—baked until the bottom is golden and crispy, with a fluffy egg filling and melted cheddar. Layer sautéed bell pepper, zucchini, onion, and spinach over the crust for a savory, make-ahead brunch bake that slices clean.
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Prep Time 20 minutes
Cook Time 48 minutes
Total Time 1 hour 8 minutes
Servings: 10 servings
Course: Breakfast
Cuisine: American
Calories: 420
Ingredients Equipment Method Notes

Ingredients
  

For the Hash Brown Crust
  • 20 oz frozen shredded hash browns Thaw and squeeze dry so the crust bakes crisp.
  • 4 tbsp unsalted butter Melted.
  • 0.5 tsp salt
  • 0.25 tsp black pepper
For the Filling
  • 1 tbsp olive oil
  • 1 red bell pepper, diced
  • 1 small zucchini, diced
  • 0.5 medium yellow onion, finely diced
  • 1 cup baby spinach, roughly chopped
  • 8 large eggs
  • 0.5 cup whole milk
  • 1.5 cups shredded cheddar cheese, divided Reserve 1 cup for the crust layer and 1/2 cup for the top.
  • 0.5 tsp garlic powder
  • 0.5 tsp salt
  • 0.25 tsp black pepper
  • 2 tbsp chopped fresh chives For garnish.

Equipment

  • 1 sheet pan
  • 1 cast iron skillet

Method
 

Preheat and prep the pan
  1. Preheat the oven to 425°F. Grease a 9x13-inch baking dish generously with butter or nonstick spray.
Build the hash brown crust
  1. In a bowl, mix thawed squeezed-dry frozen shredded hash browns with melted unsalted butter, salt, and black pepper. Press evenly into the bottom and slightly up the sides of the baking dish.
  2. Bake at 425°F for 20 minutes, until the edges turn golden and crisp.
Sauté the vegetables
  1. Heat olive oil in a skillet over medium heat. Add diced red bell pepper, diced small zucchini, and finely diced yellow onion; cook 5–6 minutes until softened.
  2. Stir in roughly chopped baby spinach just until wilted, about 1 minute. Remove from heat.
Whisk the egg mixture
  1. In a large bowl, whisk large eggs, whole milk, garlic powder, salt, and black pepper until fully combined and slightly frothy.
Assemble and bake
  1. Reduce the oven to 375°F. Spread the sautéed vegetables evenly over the baked hash brown crust and sprinkle 1 cup of shredded cheddar cheese on top.
  2. Pour the egg mixture evenly over everything, then scatter the remaining 1/2 cup shredded cheddar cheese on top.
  3. Bake at 375°F for 28–32 minutes, until the eggs are puffed, set in the center, and the top is golden; a knife inserted in the middle should come out clean.
Rest and serve
  1. Let the casserole rest for 5–10 minutes before slicing to help it firm up for clean squares. Garnish with chopped fresh chives and serve.

Notes

For the crispiest hash brown crust, squeeze the thawed hash browns very dry before mixing with the melted butter and seasonings. Store covered in the refrigerator up to 4 days; reheat individual portions in the microwave or warm the whole dish at 325°F until hot. Freezing is yes—freeze baked slices tightly wrapped for up to 2 months and thaw overnight in the fridge before reheating. For a lighter version, swap whole milk for 2% milk and use part-skim cheddar (texture stays tender).