Breakfast Sausage Spinach Mushroom Egg Bake

Here is my favorite sausage spinach mushroom egg bake recipe, with crusty bread, savory pork sausage, fresh vegetables, and a creamy egg custard loaded with melted cheddar cheese.

This egg bake is my go-to breakfast when we have family visiting or during busy weekends. I love that I can prep it the night before and just pop it in the oven in the morning. Plus, everyone gets a hot breakfast without me standing over the stove flipping eggs for twenty minutes!

What Kind of Sausage Should I Use?

You can use either mild or spicy ground pork sausage for this egg bake, depending on your preference and who you’re feeding. Breakfast sausage works great here, but Italian sausage is another solid option if that’s what you have on hand. Just make sure to remove the casings if you’re using links instead of ground sausage – you want it to crumble nicely as it cooks. If you’re looking for a leaner option, turkey sausage will work too, though it won’t have quite as much flavor as pork sausage, so you might want to add a bit more seasoning to compensate.

Options for Substitutions

This egg bake is really forgiving when it comes to swapping ingredients:

• Crusty bread: Any bread works here – sourdough, French bread, ciabatta, or even day-old sandwich bread. If your bread is soft, toast the cubes lightly in the oven for 10 minutes before using to help them hold up better.
• Ground pork sausage: You can use turkey sausage, chicken sausage, or even crumbled breakfast sausage patties. For a vegetarian version, skip the meat and add extra mushrooms or some cooked white beans.
• Bell peppers: Any color bell pepper works, or try using poblano peppers for a mild kick. You can also swap in zucchini or diced tomatoes if that’s what you have.
• Spinach: Fresh kale, arugula, or Swiss chard all work well. You can also use frozen spinach – just thaw it completely and squeeze out all the water before adding.
• Milk or half-and-half: Whole milk, 2%, or even unsweetened almond milk will work. The half-and-half makes it richer, but regular milk is totally fine.
• Cheddar cheese: Feel free to use whatever cheese you like – mozzarella, Monterey Jack, Swiss, or a Mexican blend all taste great in this bake.

Watch Out for These Mistakes While Baking

The biggest mistake when making this egg bake is not fully cooking the sausage before adding it to the casserole – any pink remaining in the meat means it needs more time in the skillet, and be sure to break it into small, bite-sized crumbles for even distribution.

Skipping the step of sautéing the vegetables, especially the mushrooms and spinach, can leave you with a watery casserole since these ingredients release moisture as they cook – always cook them until the liquid evaporates before mixing them in.

Another common error is pouring the egg mixture into a cold baking dish, which can lead to uneven cooking, so let your cooked ingredients cool for about 10 minutes before adding the eggs.

Finally, resist the urge to cut into the casserole right away – letting it rest for 10 minutes after baking helps it set properly and makes slicing much cleaner.

What to Serve With Sausage Spinach Mushroom Egg Bake?

This egg bake is pretty hearty on its own, but I love serving it with fresh fruit on the side – think sliced melon, berries, or a simple fruit salad to balance out all those savory flavors. A stack of buttered toast or some flaky biscuits are perfect for soaking up any extra egg mixture on your plate. If you’re feeding a crowd for brunch, consider adding some crispy bacon or breakfast potatoes on the side, or keep things simple with a light arugula salad dressed with lemon and olive oil. Coffee and orange juice are must-haves for the table too!

Storage Instructions

Store: This egg bake keeps really well in the fridge for up to 4 days in an airtight container. I actually think it tastes even better the next day once all the flavors have had time to meld together. It’s perfect for grabbing a quick breakfast throughout the week!

Freeze: You can freeze individual portions wrapped tightly in plastic wrap and then placed in a freezer bag for up to 3 months. I like to cut it into squares first so I can just grab one piece at a time for busy mornings.

Reheat: Warm it up in the microwave for about 1-2 minutes, or pop it in a 350°F oven for 10-15 minutes until heated through. If reheating from frozen, add an extra minute or two in the microwave or thaw it overnight in the fridge first.

Estimated Nutrition

Estimated nutrition for the whole recipe (without optional ingredients):

• Calories: 2300-2600
• Protein: 130-150 g
• Fat: 145-165 g
• Carbohydrates: 105-120 g

Ingredients

For the base:

• 4 cups crusty bread cubes (cut into 1-inch pieces)

For the filling:

• 1 cup sliced mushrooms (about 8 oz, for best flavor)
• 1 cup fresh spinach (packed, roughly chopped)
• 3/4 cup yellow onion (diced into 1/4-inch pieces)
• 1 tsp olive oil
• 2 cups chopped bell peppers (diced into 1/2-inch pieces)
• 1 lb ground pork sausage (I use Jimmy Dean)
• 2 garlic cloves (minced)
• 1 tsp dried rosemary (or Italian seasoning)

For the custard:

• 1 cup shredded cheddar cheese (I use Cabot)
• 12 large eggs
• 2/3 cup milk (or half-and-half for extra creaminess)
• 1/4 tsp salt
• 1/8 tsp black pepper

For the garnish (optional):

• green onion (optional, adds fresh flavor and color)
• chopped parsley

Step 1: Prepare the Mise en Place and Build Flavor Base

• 3/4 cup yellow onion
• 1 cup sliced mushrooms
• 2 cups chopped bell peppers
• 1 cup fresh spinach
• 2 garlic cloves
• 4 cups crusty bread cubes

Dice the onion into 1/4-inch pieces, slice the mushrooms, chop the bell peppers into 1/2-inch pieces, roughly chop the spinach, and mince the garlic cloves.

Cut the bread into 1-inch cubes and set aside.

Having everything prepped and ready will make the cooking process smooth and allow you to build layers of flavor without rushing.

Step 2: Cook the Sausage and Sauté the Vegetables

• 1 tsp olive oil
• 1 lb ground pork sausage
• 3/4 cup yellow onion
• 1 cup sliced mushrooms
• 2 cups chopped bell peppers
• 2 garlic cloves
• 1 tsp dried rosemary

Heat 1 teaspoon of olive oil in a large skillet over medium-high heat.

Add the ground pork sausage and cook for 5-6 minutes, breaking it apart with a spoon as it cooks until it’s no longer pink.

Remove the cooked sausage and set aside on a plate.

In the same skillet with the rendered fat, add the diced onion and cook for 2-3 minutes until softened, then add the mushrooms and bell peppers and cook for another 3-4 minutes until they begin to soften.

Add the minced garlic and dried rosemary, stirring for about 30 seconds until fragrant.

Finally, add the chopped spinach and stir until wilted, about 1 minute.

Return the cooked sausage to the skillet and stir everything together to combine.

This method builds deep flavor by letting the vegetables soften in the sausage fat and toasting the herbs.

Step 3: Assemble the Bread and Filling Base

• 4 cups crusty bread cubes
• sausage and vegetable mixture from Step 2

Grease a 9×13-inch baking dish lightly.

Spread the bread cubes evenly across the bottom of the dish, then pour the sausage and vegetable mixture from Step 2 over the bread, spreading it out evenly so the filling is distributed throughout.

Step 4: Prepare and Pour the Egg Custard

• 12 large eggs
• 2/3 cup milk
• 1 cup shredded cheddar cheese
• 1/4 tsp salt
• 1/8 tsp black pepper

In a large bowl, whisk together the 12 eggs, 2/3 cup milk, 1 cup shredded cheddar cheese, 1/4 teaspoon salt, and 1/8 teaspoon black pepper until well combined.

Pour this egg mixture evenly over the bread and sausage mixture in the baking dish, using a fork or spatula to gently push down on the bread so it absorbs the custard.

I like to let it sit for a minute and then give it another gentle stir to ensure the bread is saturated with the egg mixture.

Step 5: Chill and Prepare for Baking

Cover the baking dish with plastic wrap or foil and refrigerate for at least 30 minutes, or up to overnight.

This resting time allows the bread to fully absorb the egg custard and helps the flavors meld together.

When you’re ready to bake, remove the dish from the refrigerator and let it sit at room temperature for about 10 minutes while you preheat the oven.

Step 6: Bake Until Golden and Set

Preheat the oven to 375°F.

Remove the cover from the baking dish and place it in the preheated oven.

Bake for 40-45 minutes, until the top is golden brown and a knife inserted in the center comes out clean or with just a few moist crumbs.

The egg custard should be set but still slightly tender in the center.

Step 7: Rest and Garnish

• chopped parsley
• green onion

Remove the egg bake from the oven and let it cool for about 10 minutes before slicing.

This resting period allows the custard to set up a bit more and makes it easier to cut clean portions.

Garnish with fresh chopped parsley and green onion if desired for a pop of fresh flavor and color.

Slice into squares and serve warm.

Breakfast Sausage Spinach Mushroom Egg Bake

Delicious Breakfast Sausage Spinach Mushroom Egg Bake recipe with step-by-step instructions.

Print Recipe Pin Recipe

Prep Time 20 minutes mins

Cook Time 45 minutes mins

Total Time 1 hour hr 7 minutes mins

Servings 8 servings

Calories 2450 kcal

Ingredients

  

For the base:

• 4 cups crusty bread cubes (cut into 1-inch pieces)

For the filling:

• 1 cup sliced mushrooms (about 8 oz, for best flavor)
• 1 cup fresh spinach (packed, roughly chopped)
• 3/4 cup yellow onion (diced into 1/4-inch pieces)
• 1 tsp olive oil
• 2 cups chopped bell peppers (diced into 1/2-inch pieces)
• 1 lb ground pork sausage (I use Jimmy Dean)
• 2 garlic cloves (minced)
• 1 tsp dried rosemary (or Italian seasoning)

For the custard:

• 1 cup shredded cheddar cheese (I use Cabot)
• 12 large eggs
• 2/3 cup milk (or half-and-half for extra creaminess)
• 1/4 tsp salt
• 1/8 tsp black pepper

For the garnish (optional):

• green onion (optional, adds fresh flavor and color)
• chopped parsley

Instructions

 

• Dice the onion into 1/4-inch pieces, slice the mushrooms, chop the bell peppers into 1/2-inch pieces, roughly chop the spinach, and mince the garlic cloves. Cut the bread into 1-inch cubes and set aside. Having everything prepped and ready will make the cooking process smooth and allow you to build layers of flavor without rushing.
• Heat 1 teaspoon of olive oil in a large skillet over medium-high heat. Add the ground pork sausage and cook for 5-6 minutes, breaking it apart with a spoon as it cooks until it's no longer pink. Remove the cooked sausage and set aside on a plate. In the same skillet with the rendered fat, add the diced onion and cook for 2-3 minutes until softened, then add the mushrooms and bell peppers and cook for another 3-4 minutes until they begin to soften. Add the minced garlic and dried rosemary, stirring for about 30 seconds until fragrant. Finally, add the chopped spinach and stir until wilted, about 1 minute. Return the cooked sausage to the skillet and stir everything together to combine. This method builds deep flavor by letting the vegetables soften in the sausage fat and toasting the herbs.
• Grease a 9x13-inch baking dish lightly. Spread the bread cubes evenly across the bottom of the dish, then pour the sausage and vegetable mixture from Step 2 over the bread, spreading it out evenly so the filling is distributed throughout.
• In a large bowl, whisk together the 12 eggs, 2/3 cup milk, 1 cup shredded cheddar cheese, 1/4 teaspoon salt, and 1/8 teaspoon black pepper until well combined. Pour this egg mixture evenly over the bread and sausage mixture in the baking dish, using a fork or spatula to gently push down on the bread so it absorbs the custard. I like to let it sit for a minute and then give it another gentle stir to ensure the bread is saturated with the egg mixture.
• Cover the baking dish with plastic wrap or foil and refrigerate for at least 30 minutes, or up to overnight. This resting time allows the bread to fully absorb the egg custard and helps the flavors meld together. When you're ready to bake, remove the dish from the refrigerator and let it sit at room temperature for about 10 minutes while you preheat the oven.
• Preheat the oven to 375°F. Remove the cover from the baking dish and place it in the preheated oven. Bake for 40-45 minutes, until the top is golden brown and a knife inserted in the center comes out clean or with just a few moist crumbs. The egg custard should be set but still slightly tender in the center.
• Remove the egg bake from the oven and let it cool for about 10 minutes before slicing. This resting period allows the custard to set up a bit more and makes it easier to cut clean portions. Garnish with fresh chopped parsley and green onion if desired for a pop of fresh flavor and color. Slice into squares and serve warm.