Name: Cheesy Bacon, Kale, Mushroom, and Croissant Breakfast Casserole
Prep time: 25 min
Cook time: 50 min
Total time: 95 min
Ingredients: 6-7 ounces bacon (chopped); ½ cup chopped onion; ¾ cup sliced mushrooms; ½ teaspoon chopped garlic; 2 cups fresh kale (chopped); 4 large eggs; ¾ cup whole milk; ⅔ cup heavy cream; 1 cup shredded havarti cheese; 1 cup shredded gruyère cheese; 4-5 sprigs thyme (stripped); 8 small croissants (sliced)

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Mornings are made better with this Cheesy Bacon, Kale, Mushroom, and Croissant Breakfast Casserole. Made with buttery croissants, TWO types of cheese, crispy bacon, mushrooms, onion, lots of kale, garlic, and a few sprigs thyme. It’s baked until golden brown and perfectly set for a casserole the whole family is sure to love! Every bite is buttery, cheesy, and oh-so delicious.

overhead shot of savory breakfast casserole on white napkin with flowers, a plate, and a knife around on marble surface.

About The Reccipe

We’re back with something savory, and trust me…it’s a good one! Cheesy Bacon, Kale, Mushroom, and Croissant Breakfast Casserole. It might be a mouthful to say, but it is truly SO delicious.

We were inspired to make this casserole after finding some croissants left in our freezer. This recipe is literally every staple we keep in our fridge!

These are me and my mom’s go-to ingredients for omeletes/scrambles for breakfast every morning.

breakfast casserole with square slice taken out of bottom left of casserole with slice on plate beside with sprig of thyme.

angled front photo of breakfast casserole with plate with slice of casserole and sprig of time behind, an empty glass, and flowers around.

Though, to make things a bit more special, we sautéed our onions, garlic, mushrooms, and kale in bacon fat!

This adds an incredible amount of flavor to the casserole and is definitely a step you don’t want to skip!! On top of that, we opted to add two different cheeses. Gruyère and havarti.

Each cheese adds to the richness of this casserole, while also providing creamy and nutty undertones to help give each bite the best flavor.

Then, croissants. I mean, do I even have to say anything? They add an incredible amount of buttery flavor, while absorbing the custard quickly! In addition to that, they also make this casserole just a little bit more special.

overhead close up of breakfast casserole.

All together, it creates a casserole that is simply irresistible and perfect for any and every occasion.

Reasons You Will Love This Cheesy Breakfast Casserole

It’s super simple to make!
A real crowd pleaser.
Rich, creamy, buttery, and just melts in your mouth.
The perfect breakfast for any and every occasion.
Full of flavor!!

Equipment Needed

Large Skillet
Wooden Spoon
Slotted Spoon
Mixing Bowl
Whisk
Rubber Spatula
8×12 Casserole

Ingredients

(Full ingredient amounts and instructions can be found in the recipe card at the bottom of the post)

Bacon – You can use any bacon you like for this recipe! We personally love to use applewood smoked.
Onion – Yellow onion (or sweet onions!) add a wonderful flavor to this casserole.
Mushrooms – We personally love to use baby portobello mushrooms for this casserole, but you can use white button or whatever you have on hand.
Garlic – For the best flavor, it’s always best to use fresh garlic! If you don’t have fresh, you may need to add a little bit extra.
Kale – Curly leaf kale is our go-to for so many savory recipes! It adds flavor, without tasting weird after baking.
Large Eggs – Use room temperature large eggs for this recipe.
Heavy Cream – This is the wonderful richness in the custard that makes every bite irresistible.
Havarti Cheese – Adds a wonderful creaminess to this casserole.
Gruyère Cheese – A must-have! Gruyère adds a wonderful depth of flavor, while also making this casserole rich and cheesy.
Thyme – Fresh thyme adds a subtle depth of flavor to every bite.
Small Croissants – These add the wonderful buttery flavor to the casserole. In addition to flavor, the croissants also absorb the custard much faster than traditional bread…which means this casserole gets in the oven sooner!

chopped onions, grated cheese, sliced croissants, milk, eggs, sliced mushrooms, chopped kale, chopped bacon, thyme, minced garlic, and cream on marble surface.

How To Make This Cheesy Breakfast Casserole

Step 1: Sauté bacon

In a medium skillet over medium low heat, sauté bacon until crisp.

chopped raw bacon in a greased skillet on marble surface.

Use a slotted spoon to remove bacon from pan. Drain on paper towels. Set aside.

Step 2: Sauté vegetables

Pour off most of the bacon grease, leaving 1-2 Tablespoons in pan. Add onion, mushrooms, and garlic. Sauté until onions are translucent, about 3-4 minutes.

sliced mushrooms, minced garlic, and chopped onion added to skillet with bacon grease.

Stir in kale. Cook an additional 1-2 minutes, until kale is wilted. Remove from heat and set aside to cool.

Step 3: Prepare custard

In a large bowl, whisk together eggs, milk, and cream.

Add cooled vegetable mixture, bacon, cheeses, and thyme. Stir until combined.

Sautéed kale mixture, bacon, and cheese added to milk mixture.

ingredients mixed into milk and egg mixture in glass bowl.

Add the bread and stir to coat each slice in custard. Allow to stand for 20 minutes, stirring once or twice to ensure bread is absorbing mixture.

sliced croissants added on top of milk mixture in glass bowl.

Step 4: Bake

Pour into prepared pan. Bake for 50 minutes, or until set, covering with foil the last 10 minutes of baking if necessary.

Breakfast Casserole FAQ’s

How do I know when my casserole is done? If you follow the directions in the recipe card below, the casserole should be done after 50 minutes! If you’re unsure, the casserole should be puffed all the way through and shouldn’t jiggle when shaken.

Do I have to use croissants for this recipe? While croissants are preferable, as they add a lot of flavor, you really can use any kind of bread! Stale white bread is a great bread to use for this casserole.

Why did my casserole sink after baking? This is totally normal! As the casserole bakes, the steam makes it rise. Once it’s out of the oven and starts to cool, the casserole will deflate.

What To Serve With This Cheesy Breakfast Casserole

One of our favorite things to serve with this casserole is a simple salad, as this recipe is very rich and heavy! Though, you can really serve almost anything with this casserole. From a dollop of sour cream on top to buttermilk biscuits. It really depends on what you’re looking for!

angled photo of savory breakfast casserole with slice of casserole on plate above, with knife beside the casserole dish on marble surface.

How To Store

Once this is baked and cooled, you can store this casserole, covered, in the fridge for up to 2 days. To reheat it, you can either place the casserole in the oven for 10-15 minutes (or until fully reheated), or cut off a slice, place it on a plate, and microwave it for 30 seconds – 1 minute, or until reheated.

Substitutions

You can use ham or prosciutto in this recipe instead of bacon. If you do this, sauté your vegetables in some butter, as you won’t have bacon fat to sauté them in.
Any type of mushroom can be used in this recipe! A mix of different mushrooms can also be used.
Not a fan of kale? No problem! Spinach is a wonder substitute in this dish.
You can really use almost any cheese for this recipe. If you’re looking for something a little less fancy than havarti and gruyère, feel free to use low-moisture mozzarella, cheddar cheese, or even parmesan!
Really any plain bread can be used in this recipe. From a plain white bread to challah! Whatever you have on hand should work well. Just keep in mind the absorption rates will be different and the casserole may need to sit longer than 20 minutes.
To make this recipe vegetarian-friendly, omit the bacon or use your favorite plant-based bacon substitute.

Looking for more recipes like this? Here are a few you may like: Ham and Cheese Croissant Casserole, Bacon Cheddar and Chive Scones, Buttermilk Biscuits, Triple Berry Croissant Breakfast Casserole

savory casserole in white casserole on white napkin with fork and knife beside, a plate, and white flowers around.

Expert Tips

Be sure to let the croissants absorb the custard before baking! This ensures the most amount of flavor.
If you change the size of the casserole used for this recipe, you will need to adjust bake times accordingly. If you use a smaller casserole, the bake time will be longer. A larger casserole will need less baking time.
Let this casserole cool slightly before serving!

When you make this Cheesy Bacon, Kale, Mushroom, and Croissant Breakfast Casserole, leave a comment down below! We love hearing from you and answering any questions you might have! Also, be sure to tag us on social media and hashtag it #BakersTable.

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Cheesy Bacon, Kale, Mushroom, and Croissant Breakfast Casserole