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Mushroom and Swiss Breakfast Casserole

For those mornings when you want something a little more sophisticated (but still super easy), this mushroom and Swiss combo delivers! The earthy mushrooms and nutty Swiss cheese create an elegant flavor that feels fancy but comes together without any fuss. Your family will think you've been watching cooking shows—let them wonder!
Print Recipe
Prep Time 30 minutes
Cook Time 55 minutes
Total Time 1 hour 25 minutes
Servings: 8 servings
Ingredients Method

Ingredients
  

  • 2 tablespoons butter
  • 1 lb baby bella mushrooms sliced
  • 1 medium yellow onion diced
  • 2 cloves garlic minced
  • 6 cups cubed sourdough bread
  • 2 cups shredded Swiss cheese divided
  • 10 large eggs
  • 2½ cups whole milk
  • 1 tablespoon fresh thyme leaves or 1 teaspoon dried
  • 1 teaspoon salt
  • 1/2 teaspoon black pepper
  • 1/4 teaspoon nutmeg
  • 2 tablespoons fresh parsley chopped (for garnish)

Method
 

  1. In a large skillet over medium-high heat, melt butter. Add mushrooms and onions, cooking for 8-10 minutes until mushrooms release their liquid and turn golden brown. Add garlic and cook 1 minute more. Remove from heat and let cool slightly.
  2. Grease a 9x13-inch baking dish. Spread bread cubes evenly in the dish.
  3. Layer the mushroom mixture over the bread, then sprinkle with 1½ cups of Swiss cheese. Reserve remaining ½ cup for topping.
  4. In a large bowl, whisk together eggs, milk, thyme, salt, pepper, and nutmeg until well blended.
  5. Pour egg mixture evenly over the casserole, pressing down gently to ensure all bread is moistened. Cover and refrigerate overnight or at least 4 hours.
  6. To freeze: Wrap tightly with plastic wrap followed by aluminum foil. Freeze for up to 2 months. Thaw in refrigerator overnight before baking.
  7. When ready to bake, preheat oven to 350°F and let casserole sit at room temperature for 20 minutes.
  8. Cover with foil and bake for 35 minutes. Remove foil, top with remaining ½ cup Swiss cheese, and bake uncovered for 20 minutes more until puffy and golden.
  9. Let stand 10 minutes before serving. Garnish with fresh parsley and enjoy!