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Croissant Breakfast Casserole

Looking for a delicious overnight breakfast casserole recipe for your holiday celebrations? This savory Croissant Breakfast Casserole is full of ham, mushrooms, and gruyere cheese for a breakfast that will satisfy all of your guests.

Prep Time
20 mins
Cook Time
1 hr
Additional Time
8 hrs
Total Time
9 hrs 20 mins
Servings: 8 -10 servings
Course: Breakfast

Ingredients

  • ¼ cup Challenge Unsalted Butter plus extra for buttering the pan
  • 8 ounces Sliced Fresh Mushrooms such as crimini or shiitake
  • 1 large leek sliced
  • 1 medium onion diced
  • 1 teaspoon fine sea salt divided
  • 3-4 cloves garlic minced
  • 2 tablespoons whole-grain mustard
  • 1 tablespoon sherry vinegar optional
  • 8 large eggs
  • 2 cups whole milk
  • 6-8 ounces diced smoked ham
  • 6 ounces grated gruyere cheese
  • 2 ounces freshly grated Parmesan cheese
  • ½ teaspoon black pepper
  • 12 ounces croissants cut or torn into 1-inch pieces

Instructions

    Cup of Yum
  1. In medium pan, melt the butter over medium heat. Add the mushrooms, leeks, and onion with ¼ teaspoon of the salt. Saute for about 10 minutes. When the mushrooms and onions are soft and caramelized, add the garlic, mustard, and sherry vinegar and cook for 1 additional minute. Set aside to cool.
  2. In a large bowl, whisk the eggs and milk until thoroughly combined. Add the cooled mushroom mixture, ham, cheeses, and black pepper, and remaining ¾ teaspoon of salt. Gently fold in the croissant pieces. 
  3. Generously butter a 9x13-inch baking dish. Add the casserole mixture to the pan. Cover and refrigerate overnight. 
  4. In the morning, preheat the oven to 375ºF. Bake the casserole for 1 hour, or until the top is golden, the edges are crispy, and the center is set.