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Slice of egg and croissant bake with ham, spinach, cheese, and caramelized onions

Egg and Croissant Bake with Ham, Spinach and Cheese

Egg and croissant bake is a comforting brunch casserole with a tender egg custard, flaky pastry pieces, savory fillings, and rich layers of flavor. It is a hearty make-ahead-friendly dish for relaxed breakfasts and gatherings.
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Prep Time 20 minutes
Cook Time 40 minutes
Total Time 1 hour
Servings: 9 servings
Course: Breakfast
Cuisine: American
Calories: 246
Ingredients Method Notes

Ingredients
  

Filling
  • 2 tablespoons olive oil
  • 1 large yellow onion, sliced thinly
  • 2 1/2 cups diced ham
  • 2-3 oz / 85 g fresh baby spinach
  • 1 cup shredded cheese (Swiss/Gruyere mix)
Egg Mixture
  • 12 eggs
  • 1/2 cup milk
  • 1 tablespoon Dijon mustard
  • 1 teaspoon salt
  • pepper, to taste
Assembly
  • 5-6 mini croissants, torn into small pieces (or 3-4 large size)

Method
 

Preparation
  1. Heat olive oil in a large heavy pan over medium-low heat. Add sliced onions and cook, stirring occasionally, for about 30 minutes until they become deeply browned, soft, and jammy.
  2. Add ham to a skillet with a small drizzle of olive oil. Cook until the edges are browned and some fat has rendered, then add spinach and stir until wilted. Remove from heat.
  3. Whisk together eggs, milk, Dijon mustard, salt, and pepper until combined.
Assembly
  1. Preheat the oven to 350°F (177°C). Grease a 9×13 baking dish.
  2. Spread the ham, spinach, and onions in the bottom of the baking dish. Add half of the shredded cheese, pour the egg mixture over the fillings, arrange croissant pieces on top, and finish with the remaining cheese.
Baking
  1. Cover the baking dish with foil and bake for 30 minutes, depending on oven and pan size.
  2. Remove the foil and continue baking for another 5-10 minutes until the center is almost completely firm when gently jiggled and the casserole is beginning to puff.
Serving
  1. Slice the bake into portions and serve.

Notes

Make Ahead: The recipe can be prepared ahead. The cooked onion and ham/spinach steps can be completed the night before, then the remaining assembly can be done the day of baking. Avoid soaking the croissant pieces in the egg mixture overnight. Pan Size: A casserole dish slightly smaller than 9×13 creates thicker pieces and may bake closer to 40 minutes.