Fireman’s Overnight Breakfast Casserole Recipe (with sausage!)

by | Nov 8, 2019 | All, Breakfast & Brunch, Fall, Spring, Summer, Winter

This easy Overnight Breakfast Casserole recipe (made WITHOUT bread) is prepped the night before and baked in the morning – perfect for Christmas morning or any holiday brunch! 

Two hands holding a 9 x 13 Glass casserole dish filled with Overnight Breakfast Casserole.

Let’s start with the obvious question: what makes this a fireman’s casserole?

I have no idea.

This easy Fireman’s Overnight Breakfast Casserole recipe is courtesy of my mother-in-law, Cathy, and it’s been a staple at family brunches for as long as I’ve been around (and that’s been decades, friends).

Ingredients for Overnight Breakfast Casserole recipe including eggs, sausage and cheese

She got the recipe from a community cookbook, so maybe we can assume it came from a fireman or fireman’s family??

Regardless of its origin, this overnight egg casserole recipe is a delicious, make-ahead option for any brunch – holiday or not.

White casserole dish filled with cracked raw eggs.

Easy Overnight Breakfast Casserole Recipe

I totally get why Cathy relies on this recipe as an easy, make-ahead brunch recipe. Who wants to be stuck spending time in the kitchen during the holidays?

About 25 minutes of prep time the night before is all that’s required to make this cheesy egg bake. There is also a creamy mushroom sauce that we drizzle on top of the casserole. It’s totally optional (but highly recommended because who doesn’t love MORE mushrooms!?).

Once you’ve assembled the casserole, place it in the refrigerator overnight. If you like, you can make the mushroom sauce the night before, too. 

Heavy cream poured into white casserole dish filled with raw eggs.

Once morning rolls around, and all you need to do is pop the casserole in the oven an hour before guests arrive. If you made the sauce the night before, simply reheat it gently on the stove or microwave.

It doesn’t get much easier than that.

White casserole dish filled with Overnight Breakfast Casserole recipe ingredients including cheese, sausage, eggs and mushrooms.Overnight Breakfast Casserole with Sausage

Ease of preparation is one thing, but let’s not forget flavor. The Fireman’s Overnight Breakfast Casserole doesn’t disappoint there, either.

Each decadent bite is filled with savory breakfast sausage, a full dozen eggs, extra sharp cheddar cheese, loads of mushrooms, savory onion, crunchy green pepper and a hint of garlic.

Because there is no bread in this breakfast casserole recipe, it’s a great option to serve guests who have gluten sensitivities. Just be sure to check that all of your ingredients are gluten-free. 

White casserole dish filled with unbaked Overnight Breakfast Casserole.

The mushroom sauce may seem like overkill, but it’s truly the finishing touch to this dish. (Full disclosure: I use any excuse I can to add more mushrooms to my meals!)

Tip: We love the flavor of an extra sharp cheddar cheese in this recipe, but feel free to sub in your favorite cheese if you prefer something different.

Overnight Breakfast Casserole in a white baking dish. Casserole has been cut into pieces and one piece is removed.

What else should I serve with this Overnight Breakfast Casserole? 

We get it; hosting a brunch for a crowd can feel stressful. Does my house look good enough? How will I make all the food be ready at the same time? Will everyone like it? 

Our favorite way to keep the stress from creeping in when we entertain is to make as much ahead of time as possible. That includes drinks, appetizers and the full menu. 

Hand spooning mushroom sauce over a piece of Fireman's Overnight Breakfast Casserole.

This Fireman’s Overnight Breakfast Casserole is the centerpiece of any brunch, but here are also a few mostly make-ahead ideas to round out that brunch menu: 

Baked Goods:

  • These Caramel Apple Rolls can be prepped the night before and simply baked into warm gooey goodness in the morning.
  • Short on time and can’t do any morning baking? Make these Blueberry Lemon Poppy Seed Muffins the day before your brunch. Keep them loosely covered until you’re ready to serve them. 
  • No brunch is complete at our house without my Grandma’s Sour Cream Coffee Cake recipe. (The cinnamon streusel swirl is the best part!) 

Side Dishes:


Dessert Recipes: 

  • Who can refuse this dessert mashup of carrot cake and cheesecake? You get the best of both worlds with our Carrot Cake Cheesecake Bars.
  • Feeling fancy? These Vanilla Bean Panna Cotta never fail to impress guests. (But they are soooo easy and are made in advance.) 
  • It’s hard to turn down a lemon bar, but ours include tropical coconut to give these Coconut Lemon Bars an edge over all the rest. 


Two hands holding a 9 x 13 casserole dish of Fireman's Overnight Breakfast Casserole

Keep your brunch menu stress-free during the holidays with this easy recipe for Fireman’s Overnight Breakfast Casserole! 

Pin this Fireman’s Overnight Breakfast Casserole recipe for later! 

A white casserole dish filled with Overnight Breakfast Casserole with Sausage, Eggs and Cheese.

You can never have enough breakfast casserole recipes:

Breakfast Hash Brown Bake – Garnish with Lemon®

Low Carb Breakfast Casseroles – Kalyn’s Kitchen

Bacon, Tomato and Cheese Strata – Garnish with Lemon®

Baked Egg, Broccoli and Feta Breakfast Casserole – Cookin’ Canuck

Sausage and Pepper Jack Egg Bake – Garnish with Lemon®

Get all of our breakfast and brunch recipes HERE!

Collage picture of glass casserole dishes that contain Fireman's Overnight Breakfast Casserole

Yield: 12 servings

Fireman's Overnight Breakfast Casserole

Fireman's Overnight Breakfast Casserole

This easy Overnight Breakfast Casserole is loaded with sausage, eggs, cheese and veggies and is refrigerated overnight. Perfect for Christmas morning or any brunch menu!

Prep Time 8 hours
Cook Time 1 hour
Total Time 9 hours



  • 1 pound ground pork sausage (I used Jimmy Dean)
  • 8 ounces fresh sliced mushrooms
  • 1 large onion, chopped
  • 1 green pepper, chopped
  • salt and pepper
  • 12 eggs
  • 1 cup whipping cream
  • 1 pound shredded extra sharp cheddar cheese

Mushroom Sauce:

  • 10.5 ounces condensed cream of mushroom soup
  • 1/2 cup milk
  • 1/4 teaspoon garlic powder



  1. Lightly grease a 9 x 13 baking dish. Set aside.
  2. Brown sausage in a skillet over medium heat. Drain meat. Add mushrooms, onion and green pepper to the same skillet. Stir and cook over medium heat for 6-7 minutes. Return meat to the pan, stir to combine and add salt and pepper to taste. Remove from heat.
  3. Break eggs into baking dish keeping the yolks intact. Do your best to evenly distribute the egg yolks around the pan. Poke a hole in each of the yolks with a toothpick. Pour cream over eggs and top with 1/2 of cheese.
  4. Using a slotted spoon, add sausage mixture to the baking dish. Top with remaining cheese, cover with foil and refrigerate overnight.
  5. When ready to bake, preheat oven to 350 degrees. Cook covered for 30 minutes and uncovered for another 30 minutes.

Mushroom sauce:

  1. Combine soup, milk and garlic powder in a small saucepan and cook until heated through. Add additional milk to reach desired consistency. Season to taste with salt and pepper. Serve with breakfast casserole.

Nutrition Information:



Serving Size:


Amount Per Serving: Calories: 460 Total Fat: 37g Saturated Fat: 17g Trans Fat: 1g Unsaturated Fat: 16g Cholesterol: 280mg Sodium: 903mg Carbohydrates: 8g Net Carbohydrates: 0g Fiber: 1g Sugar: 3g Sugar Alcohols: 0g Protein: 25g
No brunch is complete without this easy Overnight Breakfast Casserole recipe. Made with sausage, eggs, cheese and veggies (and no bread), this egg casserole is refrigerated overnight and baked in the morning. Perfect for Christmas or any holiday!

We're the creative juices behind Garnish with Lemon. In the past 8 years, millions of people have sipped & snacked on our recipes. Need easy, delicious party food and drinks for your next shindig? You’ve come to the right place.

Our Story

About Anna

Hi, I’m Anna, a former corporate communications nerd turned food fanatic. Turns out I like cooking for others A LOT more than explaining HR policies to them. C’mon over!