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To make this tasty Overnight Croissant Breakfast Casserole, gather these simple ingredients: - 4 large buttery croissants, torn into bite-sized pieces - 6 large eggs - 2 cups whole milk - 1 cup shredded Gruyère cheese - 1 cup cooked breakfast sausage, crumbled (or a vegetarian alternative) - 1 cup baby spinach, roughly chopped - 1/2 teaspoon garlic powder - 1/2 teaspoon fine sea salt - 1/4 teaspoon freshly ground black pepper - 1/4 teaspoon ground nutmeg - Fresh chives, finely chopped for garnish Not all of these ingredients may be available. No problem! Here are some easy swaps: - Croissants: Use any flaky bread like brioche or puff pastry. - Gruyère cheese: Try Swiss or cheddar for a different flavor. - Breakfast sausage: Use crumbled tofu or mushrooms for a veggie option. - Whole milk: Almond milk or oat milk can work in a pinch. - Baby spinach: Kale or Swiss chard also make great choices. Using the right tools makes cooking easier. Here’s what you need: - Large mixing bowl - Whisk for beating eggs - 9x13 inch baking dish - Non-stick spray or softened butter for greasing - Plastic wrap or aluminum foil for overnight soaking - Oven for baking These simple tools will help you create a wonderful dish! {{ingredient_image_2}} Start by cracking six large eggs into a big mixing bowl. Use a whisk to mix them well. Add two cups of whole milk to make the eggs creamy. Sprinkle in half a teaspoon of garlic powder, half a teaspoon of fine sea salt, a quarter teaspoon of black pepper, and a quarter teaspoon of nutmeg. Keep whisking until it is smooth and well blended. This egg mixture is the heart of your casserole. Grease a 9x13 inch baking dish with non-stick spray or butter. Tear four large buttery croissants into bite-sized pieces. Spread these pieces evenly across the bottom of the dish. Next, sprinkle one cup of crumbled breakfast sausage over the croissants. If you want a vegetarian option, skip the sausage. Add one cup of roughly chopped baby spinach on top of the sausage. The greens will add color and nutrition. Now, carefully pour the egg mixture over the layers in the dish. Use a spoon to push down any croissant pieces that float up. This helps them soak up all the egg goodness. Finish by sprinkling one cup of shredded Gruyère cheese over everything. This cheese melts beautifully and adds rich flavor. Cover the dish tightly with plastic wrap or foil. Place it in the fridge overnight. This step allows the flavors to blend and makes the croissants soft. The next morning, take the casserole out of the fridge while you preheat your oven to 350°F (175°C). Bake the casserole uncovered for about 40 to 45 minutes. Look for the egg to be fully set and the top to be golden brown. Let it rest for a few minutes before slicing. Garnish each slice with fresh chives for a pop of color and flavor. Enjoy this delightful dish with your family and friends! To make your casserole great, follow these steps. First, use fresh croissants. They should be buttery and soft. Tear them into bite-sized pieces for even soaking. Next, whisk the eggs well. Combine them with milk until smooth. This makes a rich base. Add the spices for flavor. Garlic and nutmeg really enhance the taste. Layer the ingredients carefully. Start with croissants, then sausage, and spinach. This helps each bite taste amazing. Finally, pour the egg mix slowly. This ensures every piece soaks well overnight. One common mistake is not using enough eggs. Six large eggs give the right texture. Another mistake is skipping the overnight soak. This step allows flavors to blend. If you rush and bake right away, the dish may turn out dry. Make sure to cover the dish tightly. This keeps moisture in. Also, avoid using low-fat milk. Whole milk gives a creamier finish. Lastly, don’t forget to let it rest after baking. This helps the casserole set before slicing. To get a creamy texture, use whole milk instead of skim. You can also mix in some heavy cream for extra richness. When whisking the eggs, go for a light and airy mix. This helps add fluffiness. Consider adding an extra layer of cheese. Gruyère melts beautifully and adds creaminess. If you want, fold in some cream cheese into the egg mix. It creates a delightful texture. Lastly, let the casserole cool for a few minutes before serving. This helps maintain its creamy feel as you slice it. Pro Tips Use Day-Old Croissants: For the best texture, use croissants that are at least a day old. They will absorb the egg mixture better without becoming too mushy. Add Flavor Variations: Feel free to experiment with different cheeses, such as cheddar or feta, or add herbs like thyme or basil for extra flavor. Make It Ahead: This casserole is perfect for meal prep. Assemble it a day in advance and bake it fresh in the morning for an effortless breakfast. Check for Doneness: To ensure the casserole is fully cooked, use a toothpick or knife in the center; it should come out clean when the casserole is done. {{image_4}} You can easily make a vegetarian version of this casserole. Instead of using breakfast sausage, simply swap it out for plant-based sausage or mushrooms. Both options add great flavor and texture. You can also add more veggies like bell peppers or zucchini for extra nutrition. Mixing in some diced tomatoes can also brighten the dish. To make your casserole even more exciting, try adding different spices and herbs. Fresh herbs like rosemary or thyme can elevate the taste. A pinch of cayenne pepper can add a nice kick. You might also consider adding some sun-dried tomatoes for a burst of flavor. If you love sweet and savory, a handful of berries mixed in can surprise your taste buds. Gruyère is fantastic, but feel free to experiment with different cheeses. Cheddar adds a sharp flavor, while feta brings a creamy texture. For a unique twist, try goat cheese or mozzarella. You can also mix in other fillings like cooked bacon, ham, or even artichokes. The key is to choose flavors that you enjoy and that complement each other. To store leftover casserole, let it cool completely. Once cooled, cover it tightly with plastic wrap or aluminum foil. You can also transfer it to an airtight container. This helps keep it fresh. Store it in the fridge for up to three days. If you want to freeze the casserole, cut it into portions first. Wrap each piece in plastic wrap, then foil. This prevents freezer burn. Store it in the freezer for up to three months. To reheat, thaw it overnight in the fridge. Bake the thawed casserole at 350°F (175°C) until heated through, about 25-30 minutes. Use glass or plastic containers with tight-fitting lids for storage. These keep air out and moisture in. If you plan to freeze, choose freezer-safe containers. For easy portioning, consider using individual serving dishes. This way, you can grab just what you need. Yes, you can make this casserole without eggs. Use a mix of silken tofu or a plant-based egg substitute. This will keep the creamy texture. For best results, blend the tofu until smooth and mix it with milk and seasonings. This way, you still get a rich flavor. You can store the casserole in the fridge for up to three days. Make sure to cover it tightly with plastic wrap or foil. If you notice any changes in smell or appearance, it's best to toss it out. Freshness matters for taste and safety. This dish goes well with fresh fruit. Mixed berries add a bright touch. You can also serve it with a light salad for crunch. A dollop of yogurt on the side makes it feel special. These sides balance the richness of the casserole and enhance your meal. In this blog post, we covered every aspect of making an Overnight Croissant Breakfast Casserole. We discussed key ingredients, cooking tools, and step-by-step instructions. I shared tips for perfecting your casserole and ways to avoid common mistakes. You can even explore fun variations and get guidance on storing leftovers. Now, you have the knowledge to create this delicious dish. Enjoy making it and sharing it with others! Your breakfast will never be the same again.

Overnight Croissant Breakfast Casserole

A delicious and easy breakfast casserole made with buttery croissants, eggs, cheese, and sausage, perfect for a cozy morning.
Print Recipe Pin Recipe
Course Breakfast
Cuisine French
Servings 6
Calories 350 kcal

Ingredients
  

  • 4 large buttery croissants, torn into bite-sized pieces
  • 6 large eggs
  • 2 cups whole milk
  • 1 cup shredded Gruyère cheese
  • 1 cup cooked breakfast sausage, crumbled
  • 1 cup baby spinach, roughly chopped
  • 0.5 teaspoon garlic powder
  • 0.5 teaspoon fine sea salt
  • 0.25 teaspoon freshly ground black pepper
  • 0.25 teaspoon ground nutmeg
  • 1 tablespoon fresh chives, finely chopped for garnish

Instructions
 

  • In a large mixing bowl, crack the eggs and whisk them together vigorously. Add the whole milk, garlic powder, salt, black pepper, and nutmeg. Continue whisking until the mixture is smooth and well combined.
  • Preheat your oven to 350°F (175°C) if you prefer a faster preparation for the casserole. Meanwhile, grease a 9x13 inch baking dish generously with non-stick spray or softened butter to prevent sticking.
  • Begin layering by evenly distributing the torn croissant pieces across the bottom of the prepared baking dish, creating a cozy base for the casserole.
  • Sprinkle the crumbled breakfast sausage and chopped spinach over the croissant layer, ensuring even coverage for balanced flavor in every bite.
  • Carefully pour the egg mixture over the croissant and filling layers, using a spoon to push down any floating pieces of croissant to ensure they all soak up the mixture thoroughly.
  • Finish by sprinkling the shredded Gruyère cheese evenly over the top of the casserole for a rich, melty finish once baked.
  • Cover the dish tightly with plastic wrap or aluminum foil and place it in the refrigerator overnight. This allows the flavors to meld and gives the croissants time to soak up the egg mixture.
  • The following morning, remove the casserole from the fridge while preheating your oven to 350°F (175°C) for baking.
  • Bake the casserole in the preheated oven, uncovered, for approximately 40-45 minutes, or until the egg is fully set and the top is beautifully golden brown.
  • Once baked, let the casserole rest for a few minutes before slicing into generous servings. Garnish each slice with a sprinkle of fresh chives for a vibrant touch.

Notes

Serve slices on individual plates, garnished with fresh chives and paired with mixed berries.
Keyword breakfast, casserole, croissant