Croissant Breakfast Casserole with Sausage Egg & Cheese

Say good morning to a Croissant Breakfast Casserole with sausage, egg, and cheese!  This breakfast casseroles uses prepared croissants for a flaky and buttery crust that's filled to the brim with savory sausage, custardy eggs, and sharp cheddar cheese.  It's perfect for a crowd and can be prepared the night before for almost zero early morning effort.

Croissants in a 12-pack at Costco can be cheaper than bread and they give so much texture to this savory breakfast casserole. The top and edges bake up flaky and crisp while the middle is tender and rich after a soaking with a simple egg custard mixture.  Don't stop at breakfast, though!  This dish makes a perfect addition to a brunch spread or an easy make-ahead dinner entree to serve with fruit salad.

Make the most of your bulk croissant purchase and make this Croissant Eggnog Bread Pudding next!  Croissants are also a tasty vehicle for Chicken Pecan Salad.

Ingredients

I include ingredient notes here when I think they'll be helpful, including ways to source, any preparation tips, or why I've chosen a particular ingredient. Be sure to check out the recipe card below for the full list of ingredients and their quantities!

• Bulk Breakfast Sausage - Ground breakfast sausage can be mild or hot, whichever your preference is!  We prefer breakfast sausage for flavor, but you can use sweet Italian sausage as well, especially for a dinner casserole.
• Prepared Croissants - Use bakery croissants of any size, about 15 ounces in all.  If you buy them in bulk, they freeze really well when stored in an airtight bag.
• Sharp Cheddar - Shred your own sharp cheddar or use a shortcut and purchase pre-shredded cheese.  I won't tell, and no one will be able to figure it out.
• Eggs - Use 8 large eggs to prepare the simple custard that soaks into the croissants for the perfect texture.
• Milk - Just a bit of milk lightens the egg mixture. You can use non-dairy milks, skim, low-fat, or whole milk here.

Instructions

Clear a spot in your refrigerator that will hold a 9" x 13" pan or a 3-quart baking dish.

Prepare your pan by spraying it with cooking spray or greasing it with melted butter.

Slice the croissants lengthwise (but not all the way in half) using a serrated knife.  Place the croissants into the baking dish and set it aside.

Cook the sausage in a skillet over medium-high heat until it's browned, breaking it down into small crumbles.

Drain the sausage from the pan and fill each of the croissants evenly with the cooked sausage.

Sprinkle the shredded cheese over each of the croissants evenly.

Add the eggs, milk, and pepper to a large bowl.

Whisk the egg custard mixture completely.

Pour the custard over the croissants, distributing it evenly over the cheese and sausage.  Some will leak out into the pan, but it will be reabsorbed while the casserole chills.

Cover the casserole with plastic wrap and refrigerator for at least 2 hours but up to overnight.

When you are ready to bake the breakfast casserole, remove it from the refrigerator and bring it to room temperature.  Preheat the oven to 375°F and swap the plastic wrap with foil.

Bake the croissant casserole for 20 minutes covered, and then remove the foil and bake an additional 15 minutes uncovered so that it can get a golden top and the internal temperature reaches 160°F.

The casserole will be puffed up and extra toasty, give it 5 minutes to rest before you dig in.  The casserole can be served in squares, or each person can be served a sausage, egg, and cheese croissant "sandwich".

Substitutions and Variations

The substitutions listed below have been tested in this recipe and work well. If you successfully make any other ingredient substitutions, let us know in the comments!

• Swap the Sausage - Use pork sausage, chicken or turkey sausage, or even vegan breakfast sausage crumbles to make this recipe work with your dietary needs.
• Add Green Chiles - Drain a can of diced green chiles and stir it into the cooked and drained sausage.  You can swap the sharp cheddar for a pepper jack cheese for a little bit of Tex-Mex flavor in your croissant breakfast casserole.
• Use Ham - For an extra quick prep, cube up a ham steak and sprinkle the pieces into the prepared croissants in place of the sausage.

Equipment

The best tool for slicing croissants without compressing them too much is a serrated knife or bread knife.

Serving Suggestions

This croissant breakfast casserole with sausage, egg, and cheese makes the very best version of a croissant breakfast sandwich, with the filling guaranteed to stay put and the flavors perfectly melded.  You can serve the croissants this way, with six big servings, or you can slice the casserole into squares and serve eight easily.

Serve it with fruit salad, berries, or a glass of orange juice for a great start to the day!

Make This Recipe Kid Friendly

My kids enjoy this croissant breakfast casserole best with the ham variation, and they love to have it as a dinner option!

Storage

Keep the casserole refrigerated and covered while it is soaking up the egg custard, whether this is for 2 hours or overnight.  Transfer any leftovers to an airtight container and refrigerator for up to three days.

Make-Ahead Options

A croissant breakfast with casserole is a prime candidate for a make-ahead meal.  For breakfast the next day, slice up the croissants, cook up the sausage, and cover everything with the cheese and egg mixture before bedtime.  The next morning, bring it out of the refrigerator and swap the plastic with foil while the oven preheats.  You'll have some time to get coffee on board before breakfast is ready!