A breakfast casserole with mushrooms, spinach, sausage and potatoes is great for feeding a crowd. This version is easily in my top 10 breakfast casserole recipes. You can make endless variations by changing the cheese, vegetables, and meat, or you can make it vegetarian. The creamy egg mixture holds it all together, and bakes up light and fluffy, making this breakfast strata a delicious choice for brunch.
I’ll give you variations and substitutions where I can, plus helpful tips and tricks for success. Read on for this info as well as the recipe. If you’d like to skip straight to the recipe, use the jump to recipe button at the top of the post.
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Why you should make this recipe
This breakfast casserole with spinach and mushrooms can be prepared ahead of time, so you can simply slide it into the oven in the morning.
- Make ahead – This breakfast strata can be assembled the night before and refrigerated, then baked in the morning.
- Feeds a crowd – The recipe will feed 8 adults. You can easily double it if you have a bigger group.
- Versatile – You can make swaps to the ingredient list and have dozens of variations to this casserole. For example, use cooked bacon instead of sausage, swap broccoli for spinach, bell peppers for mushrooms, etc.
Potato and sausage breakfast casserole
This sausage egg potato casserole is easy to assemble and has a ton of flavor. This is something I like to make when we have guests staying the weekend, because we usually get 2 meals for four people out of one pan.
It’s also the perfect way to handle holidays. Whether it’s Mother’s Day, Christmas, Easter or even a family reunion weekend, it is the best bang for your buck. You can feed a crowd without standing in front of the stove for hours and the best part – it can be made ahead.
A hearty breakfast casserole with sausage and potatoes is the perfect make ahead breakfast for any occasion, and you can make different versions to suit different preferences or dietary needs.
- Bread – I used brioche because it is a rich and buttery bread.
- Substitution: Sourdough would be great here. You can also use up leftover dinner rolls, or any bread that is on the verge of going stale.
- Eggs – Eggs help to bind everything together.
- Onion, garlic, mushrooms and spinach – These give the casserole a ton of flavor. You can swap out, or add in any vegetables that you like.
- Milk and cream – Combined with the eggs, this forms the custard (like a quiche) that will bake up light and fluffy.
- Potatoes – Yukon gold potatoes are perfect for this strata. The skin is paper-thin, so I don’t bother peeling them.
- Thyme – Fresh herbs bring a ton of flavor and I think thyme pairs nicely with everything in this casserole.
- Ground pork – I use ground pork and season it like breakfast sausage. You can of course just buy sausage, if you like.
- Substitution: Breakfast sausage would be an easy swap.
How to make
Here’s a quick summary of how to make this breakfast casserole. Please see the recipe card at the bottom of this post for the full recipe.
Before you begin, read the recipe all the way through. This is important with all recipes, especially if you are new to cooking. Make sure you have a complete list of what you need to make the recipe, including tools and bakeware.
- Prep – Cube bread and let it dry out a bit. Cook the ground pork / sausage with the onions. Cook spinach and mushrooms, set aside.
- Coat the baking pan with butter or cooking spray, then add cubes of bread. Shingle a layer of potatoes on top.
- Add the sausage and onion mixture, spinach, and mushrooms to the casserole.
- Finish with a final layer of potatoes and pour the egg custard over the top. Bake, or refrigerate until ready to bake and serve.
When slicing potatoes, I use a Japanese slicer to make quick work of it and to ensure they are all the same thickness. Make sure the potatoes are sliced thinly, otherwise they won’t be cooked through in the casserole.
This slicer is the updated version of the same beloved slicer I've had for over 20 years.
They are used in professional kitchens all over for a reason - they are super sharp and they will hold up for a very long time.
Breakfast casserole FAQ’s
A strata is a layered casserole brunch dish. The base is a savory bread pudding with eggs and cheese.
Yes! You can assemble the casserole the night before and refrigerate overnight, to bake in the morning. It also reheats well, so leftovers are a hit.
Yes, you can freeze this for up to 3 months. Store it in an airtight container or wrapped in plastic wrap and/or aluminum foil very well before freezing.
Variations and substitutions
As with the majority of my recipes, this can be customized to suit your tastes. You can omit ingredients you don’t prefer, add in extra ingredients, swap out different cheeses, etc.
- Spicy – Add in a pinch of chipotle or ancho chili powder to give it a spicy, smoky kick.
- Vegetarian – Omit sausage and replace with extra vegetables like bell peppers and chopped broccoli.
- Extra cheesy – Sprinkle a handful of cheese into the egg custard mixture to have cheese baked in throughout the casserole.
- Sausage – I didn’t have sausage, but I had ground pork and all the seasonings used in sausage, so I made my own. A shortcut would be to use pork sausage in the tube or patties.
Chef’s Tips for making ahead
The base of this casserole is a savory bread pudding. You’ll want to soak your dried bread in the custard mixture for at least 20 minutes, or overnight to let it really absorb the liquid.
You can pre-slice your potatoes and store them in cold water in the refrigerator. In addition, you can cook the mushrooms, spinach and pork ahead of time to help speed up the process when you are ready to cook and assemble the casserole.
Helpful tools and equipment
- I use an immersion blender to make the egg custard. You can just whisk them up by hand, but the immersion blender makes them completely smooth and uniform without any bits of egg white that just won’t mix in.
- You’ll need a casserole dish to bake it in. This is the link to the same one in the photos. I use this baking dish all the time.
- Japanese slicer – I have the old green version of this mandolin. It makes quick work of slicing the potatoes and ensures that they are evenly sliced every single time.
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For the Casserole
- 6 ounces bread, about 4 1/2 cups, cubed (I used brioche) // 170g
- 1 pound ground pork (See note) // 454g
- 2 cloves garlic, minced
- 1 large yellow onion, diced
- 1 teaspoon ground sage
- 1 teaspoon fresh thyme leaves
- 1 teaspoon light brown sugar
- pinch red pepper flakes
- 8 ounces cremini mushrooms, sliced //227g
- 1 pound spinach, cooked // 454g
- 2 pounds Yukon gold potatoes (about 4 medium), sliced thinly
- 8 ounces shredded cheese (I used Colby jack) // 227g
For the Custard
- 6 large eggs
- 1 cup milk // 240ml
- 1 cup half and half // 240ml
- 1/2 teaspoon ground nutmeg
- 1 teaspoon salt
- 1/2 teaspoon black pepper
- Spread the cubed bread out on a baking sheet, in a single layer, and put it in a low oven (300°F / 150°C) for 20 minutes, tossing the bread halfway through so it is dried out on all sides. Then remove from oven and set aside. *The bread should be dried out, but not browned.
- Spray a 2.5qt / 2.5L casserole dish with non stick cooking spray, or butter the pan. Place the dried bread in the bottom of the dish.
- Whisk the ingredients for the custard together (or use an immersion blender) and pour half of the mixture over the bread.
- Lightly press down to make sure the bread is covered with egg mixture. Place in refrigerator while you cook the vegetables.
- In a large skillet over medium heat, brown the ground pork. Add diced onion, garlic, sage, thyme, brown sugar and red pepper flakes. Cook until pork is browned and cooked through. Transfer pork to a bowl to cool. Do not rinse the pan.
- In the same pan, cook mushrooms over medium heat for about 10 minutes, then remove from pan and set aside to cool.
- Next, add spinach to the pan and cook over low heat until spinach is wilted (about 4-5 minutes). Set aside.
- Start assembling: Remove the casserole dish from the refrigerator. Shingle a layer of potatoes on top of soaked bread. Then spread sausage over the potato layer.
- Place cooked mushrooms and spinach on top of sausage.
- Shingle another layer of potatoes on top of mushrooms and spinach.
- Finish by pouring the remaining egg mixture over the top and lightly pressing down to make sure the egg custard coats all of the layers and fills in the gaps. (This will help to hold everything together.)
- Cover with foil and bake at 350°F / 180°C for 50 – 60 minutes, or until a knife easily pierces the potatoes.
- Uncover, top with cheese and return to the oven for 6 - 8 minutes until cheese is melted and bubbling. Top with fresh herbs (ex: chives, thyme, parsley) while warm, if desired.
- You will need a 2 1/2 qt or 2.5 L casserole dish. The exact amount of ingredients fit perfectly inside without it bubbling over.
- You can use ground pork sausage instead of of ground pork, sage, brown sugar and red pepper flakes.
- To make this ahead, you can assemble casserole and wrap tightly in plastic wrap. Refrigerate overnight, then remove from fridge and let it come to room temperature while the oven is heating. Then bake as directed. You can also bake it straight from the fridge, but you will likely need to add a few minutes to the baking time.
Amount Per Serving: Calories: 583Total Fat: 30gSaturated Fat: 14gTrans Fat: 0gUnsaturated Fat: 13gCholesterol: 234mgSodium: 869mgCarbohydrates: 44gFiber: 5gSugar: 8gProtein: 35g
Nutrition information calculated by a third-party company as a courtesy. It is intended as a guideline only.
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