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Croissant Breakfast Casserole

Breakfast casseroles are an easy way to take the fuss out of breakfast or brunch, and this Croissant Breakfast Casserole made with flaky croissants, ham, spinach, and cheese is just about as easy and tasty as they get. Prep it the night before, pop it in the fridge overnight, then bake and serve. Brunch is ready!

A slice of breakfast casserole on a white plate with orange slices.

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I love breakfast casseroles and make this particular one pretty often. I love the combination of croissants, ham, cheese, and spinach, and it all cooks up hot and hearty and melty and delicious.

My favorite part about this Croissant Breakfast Casserole is that you prep it the night before and leave it in the fridge overnight. I will often get up a bit early to pop it in the oven in the morning, then go back to bed. Then, about an hour later, brunch is ready. It couldn’t be any easier!

Croissant Breakfast Casserole in a baking dish.

What you’ll love about Croissant Breakfast Casserole


  • Most of the work is done the night before, so your morning is free for coffee and relaxation.
  • This Croissant Breakfast Casserole is a great use of leftover ham, but you can also tweak the ingredients based on what you have on hand.
  • The combination of buttery croissants and melted cheese is pure comfort food.
  • This recipe is perfect for family gatherings or when you have guests over.

Ingredients

  • Cooking oil or butter
  • Ham – You’ll need about 10 ounces of diced ham.
  • Onions – I use sweet onions like Spanish or Vidalia. You need about 1 cup of chopped onion.
  • Cooked baby spinach – Squeeze to remove excess water before using.
  • Eggs
  • Milk
  • Heavy whipping cream
  • Dijon mustard
  • Kosher salt and pepper
  • Gruyere cheese – Shredded.
  • Green onions
  • Mini croissants – About 15-16 mini croissants or 8 large.
The ingredients for a breakfast sandwich on a marble countertop.

How to Make Croissant Breakfast Casserole

  1. Spray a 9×13-inch baking dish with nonstick cooking spray and set it aside.
  2. Heat a skillet over medium heat. Add the oil or butter, then sauté the onions until they become translucent.
  3. Add the ham to the skillet and stir to combine. Set aside.
  4. Beat the eggs in a large bowl. Whisk in the milk, heavy whipping cream, Dijon mustard, kosher salt, and pepper.
  5. Stir in the spinach and mix to combine.
  6. Add the mini croissants into the prepared baking dish, arranging them on an angle so that they overlap.
  7. Sprinkle the ham and onion mixture over the top.
  8. Pour the egg and spinach mixture over the croissants, ensuring to get liquid all around the croissants.
  9. Top with shredded Gruyere cheese.
  10. Cover the dish with foil or plastic wrap and pop it into the fridge overnight or for at least 8 hours so the liquid can soak into the croissants.
  11. Preheat your oven to 375-F and bake the casserole, covered with foil, for 40 minutes. Remove the foil and continue to bake for an additional 15-20 minutes or until the egg has set in the middle.
  12. Serve and enjoy!

Chef Jenn’s Tips

  • If using large croissants, cut them into quarters before adding them to the baking dish.
  • Feel free to add other vegetables, like mushrooms or bell peppers for extra flavor and color.
  • Gruyere is my favorite cheese in this breakfast casserole recipe, but you can add any easy-melting cheese. Mozzarella, cheddar, Jack, and Fontina are all good choices.

Recommended

Make It A Meal

This Croissant Breakfast Casserole is a standout dish on its own, but for a bigger brunch or meal, serve it with freshly baked muffins or crispy bacon for added crunch. Don’t forget a large pot of coffee or a pitcher of mimosas to wash it all down.

Storage

To store leftovers, allow the casserole to cool completely, then cover and refrigerate for up to 3 days. Reheat your leftovers in the oven or microwave until warmed through. To freeze it, wrap the casserole tightly with foil or place it in a freezer-safe container. It can be frozen for up to 2 months. Thaw overnight in the refrigerator before reheating.

A plate of Croissant Breakfast Casserole with a slice of orange on it.
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5 from 1 vote

Croissant Breakfast Casserole

Rich, creamy, and loaded with spinach, ham and cheese, this Breakfast Croissant Casserole is loaded with flavor and is an easy choice for breakfast or brunch.
Course Breakfast, brunch
Cuisine American
Keyword breakfast, breakfast casserole, croissant
Prep Time 15 minutes
Cook Time 1 hour
Servings 8 servings
Calories 592kcal
Author Chef Jenn

Ingredients

  • 15 mini croissants about 15 mini croissants, cut in half, or 8 large cut into quarters
  • 1 cup diced onion sweet onion
  • 10 ounces ham diced
  • 6 large eggs
  • 1 cup milk
  • 1 cup heavy whipping cream
  • 2 tablespoons Dijon mustard
  • ½ teaspoon salt
  • ground black pepper
  • ½ cup cooked baby spinach squeezed dry. About 8 ounces
  • 6 ounces gruyere cheese shredded

Instructions

  • Spray a 9×13-inch baking dish with nonstick cooking spray and set it aside.
  • Heat a skillet over medium heat. Add the oil or butter, then sauté the onions until they become translucent.
  • Add the ham to the skillet and stir to combine. Set aside.
  • Beat the eggs in a large bowl. Whisk in the milk, heavy whipping cream, Dijon mustard, kosher salt, and pepper.
  • Stir in the spinach and mix to combine.
  • Add the mini croissants into the prepared baking dish, arranging them on an angle so that they overlap.
  • Sprinkle the ham and onion mixture over the top of the croissants.
  • Pour the egg and spinach mixture over the croissants, ensuring the liquid is all around the croissants.
  • Top with shredded Gruyere cheese.
  • Cover the dish with foil or plastic wrap and pop it into the fridge overnight or for at least 8 hours so the liquid can soak into the croissants.
  • Preheat your oven to 375-F and bake the casserole, covered with foil, for 40 minutes. Remove the foil and continue to bake for an additional 15-20 minutes or until the egg has set in the middle.
  • Serve and enjoy!

Notes

Chef Jenn’s Tips

  • If using large croissants, cut them into quarters before adding them to the baking dish.
  • Feel free to add other vegetables, like mushrooms or bell peppers for extra flavor and color.
  • Gruyere is my favorite cheese in this breakfast casserole recipe, but you can add any easy-melting cheese. Mozzarella, cheddar, Jack, and Fontina are all good choices.

Nutrition

Serving: 1square | Calories: 592kcal | Carbohydrates: 31g | Protein: 26g | Fat: 40g | Saturated Fat: 21g | Polyunsaturated Fat: 3g | Monounsaturated Fat: 12g | Trans Fat: 0.01g | Cholesterol: 260mg | Sodium: 1059mg | Potassium: 380mg | Fiber: 2g | Sugar: 10g | Vitamin A: 2461IU | Vitamin C: 2mg | Calcium: 336mg | Iron: 2mg

A Note on Nutritional Information

Nutritional information for this recipe is provided as a courtesy and is calculated based on available online ingredient information. It is only an approximate value. The accuracy of the nutritional information for any recipe on this site cannot be guaranteed.

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