This post may contain affiliate links. Please read our disclosure policy.
Want a filling and delicious make-ahead breakfast recipe? This easy-to-make sausage egg mushroom casserole has your name on it! It's a healthy brunch recipe that's made with a crispy potato and sweet potato crust and then loaded with sausages, mushrooms, spinach, and eggs. It's a healthy start to the day that allows you to savor more quality time with your loved ones.
For another breakfast casserole with a bit of a kick, check out this chorizo breakfast casserole.
There are two of our favorite things here: veggies and protein! The base of the casserole is made with a sweet potato and regular potato hash which is cooked until it crisps up. After browning the sausage, mushrooms, onions, and spinach, it's all piled on the hashbrown crust and drenched in savory eggs!
This egg sausage mushroom casserole is made from wholesome and simple ingredients, free from any filler ingredients. This is what you need:
- Potato and sweet potato: Make a hash from the potato and sweet potato to create a hearty and delicious base with a crispy texture.
- Oil and butter: Imparts richness as you cook off the ingredients.
- Sausage: Use breakfast sausage or turn up the heat with fresh chorizo. You could even use Italian sausage!
- Mushrooms: For earthy and umami-rich depth of flavor.
- Red onion: Sautéed until sweet and aromatic. Yellow or white onion can be used if that's what you have on hand.
- Baby spinach: Brings a burst of freshness and added nutritional value.
- Eggs: Acts as a binding agent, bringing it all together while making it wholesome.
How to make sausage egg mushroom casserole
This is a breeze to prepare, making it ideal for brunch gatherings or Sunday mornings! This is what you do:
- Potato prep: Boil the potato and sweet potato, then drain and let them cool before grating them. Fry up your hash and then press it into a baking dish.
- Cook: Add the sausage, mushrooms, onion, then the spinach to the pan, adding everything to the casserole dish once cooked.
- Add eggs: Whisk some eggs in a bowl with seasoning and then pour the egg mixture into the casserole and mix it together.
- Bake and serve: Put it in the oven for 30 minutes – done!
How to make-ahead
This egg breakfast bake is not only a cinch to throw together, you can also make it ahead of time. You've got two options here:
- Make and store: Prepare the casserole as per the recipe. Eat some now and keep the rest covered in your fridge. Before rushing off to work in the morning, cut a slice to eat on the go. Or get real fancy and warm it up. It's great both ways!
- Make before bake: Prep everything but stop short of putting it into the oven. Wrap the casserole tightly and keep it in your fridge until shortly before you're ready for brunch, then pop it in the oven 30 minutes before serving. You can't beat hot and fresh out of the oven! It's an ideal way to spend more time with family on Christmas morning, too!
What to serve with sausage egg mushroom casserole
This is a hearty breakfast that works well as a standalone dish next to a creamy almond butter latte or strawberry kiwi smoothie. If you're looking to host a spread for brunch, serve beside a breakfast salad and some homemade breakfast sausage patties. Make some mimosas, too!
While an egg casserole sounds like breakfast food, breakfast is allowed at any time of the day! Serve it up for an easy, delicious lunch or dinner alongside sweet potato wedges, roasted vegetables, or a crunchy greek salad.
What type of sausage should I use in this sausage breakfast casserole?
We use breakfast sausage links and roughly chop them up before adding them to the frying pan.
Can I add anything else?
Sure! This sausage egg mushroom casserole is versatile – sprinkle some thyme or chives on top or add some cherry tomatoes or bell peppers. Grate some cheddar cheese and add to the egg mixture, or drizzle over some hot sauce before digging in!
What type of mushrooms should I use?
You can opt for whatever mushrooms you have in the fridge or find at the grocery store. We usually get cremini, button, or baby bella mushrooms.
Can I store any leftovers?
Absolutely! Keep it in an airtight container in the fridge for up to 3-4 days. You can eat it straight out of the fridge or reheat it in the oven.
- 1 large potato
- 1 medium sweet potato
- 1 tablespoon EACH: oil and butter
- 1 lb breakfast sausage (chopped)
- 1 lb mushrooms (sliced)
- 1 small red onion (sliced)
- 10 ounces baby spinach
- 12 large eggs
- 1 teaspoon sea salt
- ½ teaspoon black pepper
- Place the potato and sweet potato into a pot and cover with water. Bring to a boil then reduce the heat and simmer until soft but not falling apart. Drain and set aside to cool, preferably in your fridge. When they're cold, peel and then grate them.1 large potato, 1 medium sweet potato
- Turn your oven to 350 degrees Fahrenheit. Heat the oil and butter in a large frying pan. Add the grated potatoes and cook, turning a few times, until there are lots of dark and crispy spots on the hashbrowns. Transfer them to a 9×11" casserole dish and press to create a crust.1 tablespoon EACH: oil and butter
- Add the sausage to the same pan you used for the potatoes. Cook until it is well browned, about 10 minutes. Transfer to the casserole dish.1 lb breakfast sausage
- Add the mushrooms to the pan and cook until they are browned, about 10 mins. Add them to the casserole.1 lb mushrooms
- Cook the onion until it is soft and golden, about 5 minutes. Add the spinach and let it wilt. Add both to the casserole and gently mix, being careful not to disturb the crust.1 small red onion, 10 ounces baby spinach
- Whisk the eggs in a large bowl with the salt and pepper. Pour the eggs over the casserole and carefully mix.12 large eggs, 1 teaspoon sea salt, ½ teaspoon black pepper
- Bake for 30 minutes, or until the casserole has set in the center.
We have thoroughly tested this recipe for accuracy. However, individual results may vary. See our full recipe disclosure here.