This overnight breakfast bake is made with toasted, buttery croissants, spinach, mushrooms, eggs and freshly gruyere cheese. It’s prepped the day before and enjoyed the next morning!

This breakfast will make your Christmas morning magical. 

overnight breakfast bake

I promise!

It’s toasty and buttery and satisfying and one of the most delicious things you will EVER eat.

toasted croissants

See, this croissant bake was one of the great things to come out of 2020 for us. 

I discovered this about a week before Christmas. We get speciality sourdough and bread products through a local baker, and he did croissants for Christmas! I ordered them with this in mind knowing that we probably wouldn’t eat the croissants otherwise.

Oh.My.GOSH.

egg and cheese

This overnight bake is not only the best I’ve ever tried, it’s the only one I’ve ever truly LOVED. 

I’ve made stratas before and those are good. I’ve tried some of those farmer breakfast casseroles. Meh. I’ve done hash brown things. Eh. 

THIS is the best overnight breakfast bake and the only one you really need.

toasted croissants

Now here’s the deal. It’s super decadent. Very rich. It’s filling and hearty. A little bit goes a long way, and you definitely want to make this for a crowd. Even better if it’s a special occasion or a holiday, but of course it doesn’t have to be.

This is out of this world.

I realize that I sound like an exaggerating crazy dramatic person (which I am) but it is super true.

overnight breakfast bake ready for the oven

The original recipe is from the NY times. That one calls for sausage, and that’s how I made it last year for Christmas – completely as written. The thing is that I don’t love sausage at all. It’s not the sausage as much as the fennel seeds, but I rarely cook with sausage. In fact, so many of you ask all the time where all my recipes with sausage can be found!

I don’t love it so I don’t have many recipes with it.

Eddie likes it though, so I tried the recipe as is. 

Even with the sausage, I still thought the croissant bake was outstanding. I mostly ate around the sausage though?. So after making it a few more times and putting a few twists on it, I did away with the sausage.

I KNOW.

overnight breakfast bake

This probably sounds ridiculous to some of you and I assure you that you can add the sausage in. But for me? I love this with straight up vegetables.

2009 me is seriously freaking out over 2021 me.

YEP.

I used a mix of onions, mushrooms, spinach and garlic to bring this to life. A classic veggie combo. These taste SO delicious against the crispy croissants, melty gruyere cheese, eggs and herbs. So freaking good.

overnight breakfast bake

Overnight croissant bake secrets! 

  • Toasting the croissants is KEY. This brings so many delicious caramelized flavor bits to the surface and adds texture to the dish. Don’t skip this part! It only takes a few minutes.
  • Yes yes yes: this much egg, milk and cheese is really necessary here. It’s a rich, decadent breakfast bake that tastes best this way.
  • You can make this a clean-out-the-fridge dish for sure. Add almost anything you want, including sausage or bacon, more greens or vegetables, different cheeses and spices and it will work! 
  • Prepping this overnight is the best way to make it. The original recipe noted as long as it was refrigerated for 4 to 6 hours it would be fine. I personally do not think that is the case! Yes, it’s FINE, I guess. But it’s not great. This tastes best when it sits overnight for at least 8 hours or even a bit longer. I’m telling you, it’s the best. I’ve made it both ways multiple times.

croissant breakfast casserole

Now the only downside? This isn’t the prettiest thing to photograph so you may not grasp the deliciousness of it from the photos. JUST TRUST ME though. 

It’s buttery, crunchy, savory, cheese and satisfying. The best!

overnight croissant breakfast bake

Overnight Breakfast Bake

Overnight Croissant Breakfast Bake

This overnight breakfast bake is made with toasted, buttery croissants, spinach, mushrooms, eggs and freshly gruyere cheese. It's prepped the day before and enjoyed the next morning!
5 from 84 votes
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Ingredients

  • 5 to 7 large croissants, sliced in half lengthwise
  • 2 tablespoons unsalted butter
  • 1 sweet onion, diced
  • 2 garlic cloves, minced
  • 10 ounces cremini mushrooms, chopped
  • 8 ounces fresh baby spinach
  • kosher salt and pepper
  • 8 large eggs
  • 2 ½ cups milk
  • 1 cup heavy cream
  • 8 ounces gruyere cheese, freshly grated
  • fresh chopped parsley, for topping
  • parmesan cheese, for topping

Instructions 

  • Preheat the oven to 450 degrees F.
  • Place the croissants cut-side up on a baking sheet. Bake for 5 to 8 minutes, until the croissants are toasty. Remove and let them cool slightly, then chop or tear them into pieces.
  • Heat the butter in a large skillet over medium-low heat. Stir in the onions and garlic and cook for 5 minutes. Stir in the mushrooms and cook for another 5, until the mushrooms are plump and juicy. Stir in the spinach until it wilts. Sprinkle everything with a big pinch of salt and pepper and stir.
  • Brush a 9x13 baking dish with melted butter. Combine the croissant pieces and the spinach/mushroom mixture together in the dish and toss well, until everything is combined.
  • In a large bowl, whisk together the eggs, milk, heavy cream and a big pinch of salt and pepper. Stir in 1 cup of the grated cheese. I also like to stir in a handful of fresh chopped herbs, like parsley and chives, but it’s up to you! Place the rest of the cheese in a bag stored in the fridge.
  • Pour the egg mixture over top of the croissant mixture in the baking dish. Press any of the croissants into the egg liquid, making sure they are covered and absorbed the eggs.
  • Cover the dish with plastic wrap and refrigerate 8 hours, or overnight.
  • Preheat the oven to 350 degrees F. Remove the dish 30 minutes before baking to take the chill off.
  • Remove the plastic wrap. Top with remaining grated cheese. Bake the dish uncovered for 45 minutes. Top with extra parmesan and a sprinkle of parsley before serving. Serve!

Notes

slightly adapted from ny times
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overnight breakfast bake