Your holiday brunch menu just got a lot easier with this recipe for a make-ahead Fireman’s Overnight Breakfast Casserole! 

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 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).

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 breakfast casserole recipe is a delicious, make-ahead option for any brunch – holiday or not.

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 20 minutes of prep time the night before is all that’s required to make this casserole. You can just make the casserole the night before or make both the casserole and the mushroom sauce.

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.

It doesn’t get much easier than that.

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.

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.

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

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. 

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. 


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! 

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

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


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

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

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 Fiber: 1g Sugar: 3g Protein: 25g