If you love the ease of breakfast casseroles, you need this recipe for Overnight Croissant Breakfast Bake in your life ASAP! Sausage, onions, sautéed spinach, eggs, and buttery croissants all topped with melty cheese. You have officially died and gone to breakfast casserole heaven!

I love a good breakfast casserole. What’s not to love about waking up, turning on the oven and about an hour later pulling this out of the oven?!

Of all the breakfast casserole recipes I have on A Bountiful Kitchen, this one is my favorite, and I believe the best breakfast casserole recipe!

You may be wondering why I use croissants in this breakfast casserole? The trouble with many breakfast casseroles is they look decent when pulled right out of the oven, but quickly deflate into a flat dish that looks less than appetizing. Our Overnight Croissant Breakfast Bake is everything you love in breakfast foods all combined into one beautiful delicious dish.

This recipe takes overnight casseroles to the next level. When I first started making breakfast casseroles in the 80’s, recipes often instructed to butter slices of bread, which made the casserole buttery and delicious. The croissants mimic the buttered bread, but in a next-level way! The flaky layers of croissants soaked in eggs and half and half are similar to a rich bread pudding texture I know you will love!

How to make this easy Breakfast Casserole:

1. Tear the croissants into pieces and place in a greased 9×13 dish.
2. Brown the sausage, drain grease and place on top of croissants in dish.
3. Cook the onion and spinach, pour on top of sausage, top with cheese.
4. Beat the eggs, half and half and add seasonings.
5. Pour over cheese in pan.
6. Cover with foil, refrigerate overnight.
7. Preheat oven, bake 30 minutes with foil on top, 30 minutes without.
8. Let cool, top with chili sauce

Ingredients needed for Overnight Croissant Breakfast Bake:

• 4-6 large croissants (day old are best)
• 1 lb Italian or spicy sausage
• 2 cups chopped onion
• 1-2 cups fresh spinach
• 2 cups grated Cheddar Monterey Jack, Pepper Jack, Mozzarella, or a combo
• 12 large eggs
• 1 1/2 cups half and half
• 1 teaspoon dry mustard

We like to serve this with sweet rolls, fresh fruit and cocoa!

This recipe originally posted in 2014, updated with new photos and content September, 2023.

5 from 2 votes

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Overnight Croissant Breakfast Bake

This easy to make breakfast casserole is my favorite of all the breakfast casseroles! Simple yet delicious with a bit of onions and spinach for color and flavor. The croissants take this ordinary breakfast casserole over the top!

Course Breakfast, brunch

Cuisine American

Keyword breakfast casserole, croissant, eggs, overnight recipe

Prep Time 15 minutes

Cook Time 1 hour

refrigeration 8 hours

Total Time 9 hours 15 minutes

Servings 12

Author Si Foster

Ingredients

• 4-6 large croissants day old are best
• 1 lb Italian or spicy sausage you may use more if desired
• 2 cups chopped onion
• 1-2 cups fresh spinach
• 2 cups grated Cheddar Monterey Jack, Pepper Jack, Mozzarella, or a combo
• 12 large eggs
• 1 1/2 cups half and half
• 1 teaspoon dry mustard
• 1 teaspoon salt
• 1 teaspoon pepper ground pepper

Instructions

1. Grease a 9×13 or large casserole dish.
2. Tear the croissants into large chunks and lay in pan close together. The rolls should cover the bottom of the pan.
3. Brown the sausage in a Teflon frying pan, drain grease and place cooked sausage in a dish lined with paper towels to collect any extra grease. Press the paper towels around the sausage to squeeze out any remaining grease. Pour the meat on top of the croissants in dish, distribute evenly.
4. Using the pan the meat was cooked in, wipe out pan with a paper towel and place the pan back on the stove at medium high heat. Cook the chopped onion for about 5 minutes or until softened, add one tablespoon oil or butter if needed. Add spinach to pan and cook just until the spinach is wilted. Pour cooked onions and spinach over top of sausage. Top with grated cheese.
5. Beat the eggs and half and half together in a blender or bowl. Add the dry mustard, salt and pepper.
6. Pour this mixture over the rolls in the pan. Cover with foil that has been greased (on side facing eggs) and store overnight in refrigerator.
7. The next morning, remove casserole from fridge, preheat oven to 375 and place rack in middle of oven.
8. Bake covered for 30 minutes, then carefully remove foil and bake until top is slightly puffed and custard is set in center, about 30 minutes more.
9. Let cool for about 10 minutes, cut into 12 squares and serve immediately with chili sauce and or salsa.

Recipe Notes

-The meat may be cooked and kept in fridge for up to three days before assembling. Or you may cook meat and freeze ahead of time.