Cheesy Croissant Breakfast Casserole - So Good, So Cheesy! (2024)

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!

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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!

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.

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.