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This make-ahead Overnight Croissant Breakfast Casserole is perfect for Christmas morning, Easter or Mother’s Day! Flaky croissants, savory sausage, and melty cheese make this delicious brunch as effortless as it is decadent.

Overnight croissant breakfast casserole on a plate.

Although I’m a big an of a fancy breakfast, I find that on holidays I prefer one that can be made ahead of time. Rather than scrambling in the kitchen, I would rather sit back with my coffee and watch my kids open presents while breakfast bakes away in the oven. That is why I love this Make Ahead Croissant Breakfast Casserole!

Ingredients for overnight croissant breakfast Casserole - croissants, milk and cream, breakfast sausage, bell peppers, onions, eggs, gruyere cheese, salt, pepper and olive oil.

In past years we have enjoyed my Overnight Croissant French Toast or Eggnog Cinnamon Rolls, however we decided that this year we wanted a more hearty and savory breakfast to avoid the sugar high. Overnight Croissant and Sausage Casserole fit the bill.

Ingredients for Overnight Croissant Breakfast Casserole

  • Croissants – about 1 pound, which was 6-7 Croissants for me.
  • Breakfast Sausage – you can use sweet or hot Italian sausage as well, whatever you prefer! I like to buy bulk/ground sausage, but if you can only find links, remove the casings.
  • Onions and Bell Pepper – adds extra savory flavor and a little color! I used red and green bell peppers, but any color will work.
  • Gruyere Cheese – I love the flavor here, but you can also use sharp cheddar or Swiss. I recommend buying a block and shredding it yourself for the best results.
  • Eggs – the base of the casserole! These bind everything together while adding structure.
  • Milk and Cream – I used a combination of whole milk and half and half. If you don’t have half and half, use a mixture of whole milk and heavy cream, or all milk. Use whole milk for the creamiest results.
  • Salt and Pepper – I used a little kosher salt. Go easy on the salt as the sausage and cheese are already salty. I added about 1 teaspoon to the whole dish.

Can I use store-bought croissants for the overnight croissant breakfast casserole?

Yes, store-bought croissants work well here. I used some from Costco. For the best results, you want to toast the croissants. I found that just a few minutes in a 425 degree oven worked perfectly. Just watch them closely because they can go from golden to burnt in a flash! Tearing the croissants before toasting gives you the most surface area to soak up the custard.

Can I prepare the casserole and bake it immediately instead of overnight?

While it’s designed for overnight prep, you can bake it the same day; just allow the ingredients to soak for at least 1 hour.

Close up of make ahead breakfast casserole.

How long can the prepared casserole sit in the refrigerator before baking?

I recommend baking it within about 12 hours of assembling for optimal freshness, but you can extend to 24 hours if needed.

Slice of croissant breakfast casserole on a plate.

Can I freeze the overnight croissant breakfast casserole leftovers?

Yes, you can freeze the leftovers. Wrap the individual portions in foil, then store in a freezer bag. Leftovers can be kept in the freezer for up to one month.

How long are leftovers good in the fridge?

Leftovers are good for 2-3 days when stored properly.

How do I reheat leftovers of the croissant breakfast casserole?

Wrap in foil and reheat in the oven at 350 degrees for 5-10 minutes or until heated through. You can also reheat this in the air fryer for great results.

Slices of make ahead breakfast croissant casserole on a plate.

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Overnight Croissant Breakfast Casserole

Prep 45 minutes
Cook 45 minutes
overnight time 8 hours
Servings 8 servings


  • 1 pound croissants about 6 or 7
  • ¾ pound breakfast sausage ground. Remove casings if bulk not available.
  • 1 tablespoon olive oil
  • 1 small onion diced
  • 1/2 red bell pepper diced
  • 1/2 green bell pepper diced
  • 8 large eggs
  • 2 cups whole milk
  • 1 cup half and half or heavy cream
  • 2 cups Gruyère grated, divided
  • 1 teaspoons kosher salt
  • ½ teaspoon black pepper
  • ¼ tsp garlic powder
  • 1 tablespoon unsalted butter for greasing baking dish


  • Preheat oven to 425 degrees. Tear croissants into large bite sized pieces and spread on an even layer on a baking sheet.
  • Toast for 3-5 minutes in the oven. Keep a close eye as they can brown quickly. Remove when golden brown and allow to cool.
  • Meanwhile, heat a large skillet over medium high heat. Brown the breakfast sausage then remove from pan and set aside.
  • Add olive oil to pan, then add onions and bell peppers, along with a pinch of salt. Sauté until soft and golden, 5-10 minutes. Set aside to cool.
  • Prepare a 9×13 baking dish by liberally buttering the inside, set aside.
  • In a large bowl, whisk together eggs, milk and half and half, salt, pepper, garlic powder.
  • Add browned sausage, peppers, onions, and 1 and 1/2 cups of grated gruyere cheese.
  • Add croissants and toss until everything is fully combined and croissants are fully moistened.
  • Transfer contents of the bowl to the baking dish, pouring any excess liquid on top of the mixture. Arrange mixture in an even layer. Top with a piece of parchment paper (keeps foil from sticking), than cover with foil. Refrigerate at least 1 hour or overnight.
  • When ready to bake, remove from fridge about 30 minutes before baking. Sprinkle remaining half cup of cheese over the top evenly. Preheat oven to 350 degrees F.
  • Bake covered for about 30 minutes. Remove cover and bake for 10-15 minutes longer, until top is golden and there is no visible liquid. Allow to sit for 15 minutes before slicing and serving.


Leftovers are good for 2-3 days in a sealed container in the refrigerator.
To freeze leftovers, wrap in foil and then place in a freezer bag. Leftovers can be frozen for up to 4 weeks.
To reheat, wrap in foil and warm in a 350 degree oven for 5-10 minutes, or until heated through. 


Serving: 1serving | Calories: 672kcal | Carbohydrates: 33g | Protein: 30g | Fat: 47g | Saturated Fat: 22g | Polyunsaturated Fat: 4g | Monounsaturated Fat: 16g | Trans Fat: 0.2g | Cholesterol: 290mg | Sodium: 1120mg | Potassium: 443mg | Fiber: 2g | Sugar: 12g | Vitamin A: 1515IU | Vitamin C: 17mg | Calcium: 496mg | Iron: 3mg

Nutrition information is automatically calculated, so should only be used as an approximation.

Additional Info

Course: Breakfast, Brunch
Cuisine: American
Did you like this recipe?Please comment, rate and share! And don’t forget to tag me on Instagram @foxandbriar AND #foxandbriar so I can see what you made!
Hello! I’m Meghan.

I am so glad that you are here! I am the recipe developer, photographer, and writer here at my blog Fox and Briar. I am a passionate, self-taught home cook and believe that most things are better homemade and that good food doesn’t need to be complicated.

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