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Ham and Cheese Croissant Casserole

Ham and cheese croissant casserole with flaky torn croissants baked until puffed and deeply golden. Savory egg-and-gruyère custard holds diced ham and creates a bubbly, caramelized top.
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Prep Time 15 minutes
Cook Time 40 minutes
soaking/resting 30 minutes
Total Time 1 hour 25 minutes
Servings: 8 servings
Course: Breakfast
Cuisine: French-American
Calories: 620
Ingredients Equipment Method Notes

Ingredients
  

croissants and fillings
  • 6 croissants large croissants, torn into large pieces
  • 1.5 cup diced ham
  • 1 cup Gruyère or Swiss cheese, shredded divided; use 1 cup for the first layer
  • 0.5 cup Gruyère or Swiss cheese, shredded divided; use remaining 1/2 cup for topping
egg custard
  • 6 eggs large eggs
  • 2 cup whole milk
  • 0.5 cup heavy cream
  • 1 tbsp Dijon mustard
  • 1 tsp garlic powder
  • 0.25 tsp salt to taste
  • 0.25 tsp black pepper to taste
  • 1 tbsp fresh thyme for garnish

Equipment

  • 1 sheet pan
  • 1 Dutch oven

Method
 

Assemble
  1. Grease a 9x13 dish and arrange the torn croissant pieces in an even layer. Make sure the pieces are in large chunks so they bake up flaky.
  2. Scatter the diced ham and 1 cup of the shredded gruyère (or Swiss) evenly over the croissants. Distribute it across the dish so every slice has filling.
  3. Whisk the eggs, whole milk, heavy cream, Dijon mustard, garlic powder, salt, and black pepper together until smooth. Pour the custard over the croissants and press down so the bread absorbs it.
  4. Let the casserole rest for 30 minutes to soak at room temperature. If making ahead, cover and refrigerate overnight for deeper custard absorption.
Bake and serve
  1. Preheat the oven to 350°F and set the rack to the middle position. Top the soaked casserole with the remaining cheese before baking.
  2. Bake at 350°F for 35–40 minutes, until the casserole is puffed and the top is deeply golden with bubbling cheese at the edges. Rotate the pan once if your oven has hot spots.
  3. Garnish with fresh thyme and let the casserole rest briefly before serving warm. Sprinkle extra thyme right over the golden top so it stays fragrant.

Notes

Pro tip: Press down firmly after pouring the custard so the center soaks, then let it sit undisturbed until baking for the best custard set. Refrigerate leftovers in a covered container for up to 3 days; reheat in a 325°F oven until warmed through. Freezing is not recommended because croissant texture can soften after thawing. For a lighter option, use half-and-half instead of heavy cream (keep the milk amount the same).