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Sausage + Onion Spinach Egg Casserole

This spinach egg casserole is an easy, nutritious breakfast. Packed with spinach, sausage and onions, it’s a healthy option for busy mornings. Freeze and reheat for the ultimate meal prep!

Overhead view of squares of spinach egg casserole cooling on a rack

Egg casseroles are one of my favorite things to make and have on hand. They’re less work than egg muffin cups (and let’s be honest – you don’t have to wash the muffin tin!)

You can make a pan and keep it in the fridge, and simply reheat squares for a meal.

We’ve used this spinach egg casserole for breakfast, but also lunch and dinner. It doesn’t discriminate and makes a great meal anytime of the day, without having to think much about sides or things to go with it.

I serve it with some fresh fruit and everyone in the house is happy – especially me, because I saved time on cooking that day!

I included a mild italian sausage as well as some chopped onion to take the flavor up a notch. You can follow my recipe, or get creative and add your own ideas. I’ve included some alternatives below.

What goes in spinach egg casserole

Spinach

This recipe calls for frozen spinach, which needs to be defrosted first. Frozen spinach contains a LOT of water, which typically cooks off when you’re using a pan.

We have to drain the water out first, so as not to float our casserole. You’ll be able to pack a lot more spinach in density-wise. If you were to try and use fresh, you wouldn’t be able to use nearly as much volume.

Defrost your spinach first, then wring it out. Just squeeze and squeeze until you can’t squeeze any more water out of it. Then put it in a bowl and break it up with a fork, so it’s not all stuck together.

If you’re looking for other ways to use frozen spinach, check out The Kitchn’s list here. (Don’t you know, her first option is…put it in an egg casserole!)

Sausage

I used one pound of ground mild italian sausage. You’ll want to cook the sausage before putting it into the casserole.

Try to get the cleanest sausage you can, ingredients-wise. A lot of them are full of fillers and junk and sugar. I prefer to make my own – you can find my breakfast sausage here and my spicy chorizo here.

I’ll be honest, for this recipe I did NOT make my own. I managed to find a package of mild italian sausage at the grocery store that did not include a bunch of junk ingredients. It wasn’t perfect, but it saved me on time, so I rolled with it. The only offensive thing in it was a bit of sugar.

Chop your onion, and cook it with your sausage, add your minced garlic, then set that mixture aside.

Eggs + milk

In another bowl, whisk your eggs with your almond milk, ghee, and salt. If you’re not dairy free, you can use regular milk in a 1:1 sub.

You can purchase ghee at most stores, or make your own. It’s clarified butter, or just butter where all the milkfat solids have been removed, making it essentially dairy free. Thrive Market has a great option here.

Flour

To keep this recipe gluten free, grain free, and paleo, I used cassava flour. Cassava flour is a great substitute in recipes like this one, and can be used in a 1:1 ratio. I use Thrive Market’s store brand and have had great results with it.

(That’s not necessarily true when it comes to baking, so be sure to do your research. You can find out all about all purpose flour substitutes and how to use them in my post here!)

Using flour can help with keeping the egg casserole from deflating when you take it out of the oven. It can help the eggs keep their structure. Often times people think they just need to cook the casserole longer, which can end up with results that are dry and unappetizing.

The combination of eggs, milk, and flour can help keep the casserole fluffy and prevent it from becoming “sunken in”

How to make spinach egg casserole

Once you’ve got your ingredients prepped as described above, it’s time to put it all together.

Start with putting the spinach and the sausage mixture into your pan and mixing well. Add the flour of your choice and toss to coat. It will look powdery; this is ok!

Overhead view of spinach egg casserole coated with flour

Next, pour your egg mixture into the dish.

Close up shot of eggs being poured into pan of spinach egg casserole

Now, you want to make sure your entire sausage and spinach mixture is covered by the egg mixture.

You can attack this one of two ways – with a kitchen tool (I use a flipper), or with your hands. Either one will work fine. Just push down until everything is submerged/coated in the egg mixture.

Overhead view of spinach egg casserole before baking

Then, bake! Cooking time may vary depending on your oven.

How to know when egg casserole is done

You’re looking for the eggs to be firm and a knife to come out clean when poked in the center.

Don’t overcook it! I like to poke a knife in the middle, and then while the knife is in there, pull back a bit. It’ll make a little hole, and if the hole fills with liquid, it’s not done yet.

When the hole stays empty, your egg casserole is done!

Allow to cool slightly, then cut into squares and serve. Serve with a pretty branch of grapes for breakfast, or with a small greens salad for lunch or dinner.

Yes, more greens – you can never have too many!

squares of spinach egg casserole stacked on a plate

Spinach egg casserole variations

There are lots of other ways you could make this spinach egg casserole.

If you prefer to omit the meat, fill the space with veggies. Bell peppers, mushrooms, or or any other tender vegetable will cook well in this spinach egg casserole.

Be wary of things that would require a longer cooking time, such as potatoes, carrots, or other hardy root vegetable.

They will likely not cook all the way through and be a bit crunchy, unless you pre-cook them ahead of time before including them in the dish.

If you’re not dairy free, you can use cow’s milk.

If you’re not gluten free, you can use regular flour.

All substitutions would be done in a 1:1 ratio.

Freezing egg casserole

Egg casserole can be frozen easily. It will keep in a regular freezer for 2-3 months, or in a deep freezer for 5-6 months.

I prefer to cook mine, allow it to cool, then cut it into squares. You can wrap the squares and freeze them individually for an easy breakfast option.

Just pull them out the night before and stick them in the fridge to defrost, then pop them in the oven to warm them up for eating.

I recommend reheating at a slightly lower heat, covered, in order to prevent drying out. Usually 300° for about 20 minutes wrapped in foil does the trick!

Sausage + Onion Spinach Casserole

Sausage + Onion Spinach Casserole

Yield: 9 servings
Prep Time: 10 minutes
Cook Time: 40 minutes
Total Time: 50 minutes

This spinach egg casserole is an easy, nutritious breakfast. Packed with spinach, sausage and onions, it's a healthy option for busy mornings. Freeze and reheat for the ultimate meal prep!

Ingredients

  • 2 10oz boxes frozen spinach
  • 1 small onion, chopped
  • 1 lb cooked sausage
  • 1 1/2 tsp minced garlic
  • 1 tsp salt
  • 1/2 cup cassava flour
  • 3 large eggs
  • 1 cup almond milk
  • 1 Tbsp ghee

Instructions

  1. Preheat the oven to 350°.
  2. Defrost and drain the frozen spinach, squeezing out the excess water.
  3. In a bowl, combine the drained spinach, cooked sausage, chopped onion, minced garlic and salt. Stir well to combine, breaking up any large clumps of spinach that stick together.
  4. Add the cassava flour to the mixture and toss to coat. Everything will look powdery, this is ok! Spread the mixture into a square baking dish. (Mine is 8x8, you could also use a 9x9.)
  5. In another bowl, whisk together the eggs, almond milk and ghee until combined.
  6. Pour the egg mixture into the pan, pressing down on the spinach and sausage mixture to get everything submerged.
  7. Bake in the oven for 30-40 minutes or until firm and eggs are cooked through.
  8. Cut into squares and serve!

Notes

For the sausage, you can make your own or use store bought. If you are on Whole30, check your ingredient lists, or make your own using this recipe!

I have not tried this recipe with other alternative flours other than cassava. You can try others but I can't say if you will get the same results. Regular flour should work without issue in a 1:1 exchange.

Nutrition Information:
Yield: 9 Serving Size: 1
Amount Per Serving: Calories: 249Total Fat: 18gSaturated Fat: 6gTrans Fat: 0gUnsaturated Fat: 9gCholesterol: 96mgSodium: 764mgCarbohydrates: 11gFiber: 3gSugar: 2gProtein: 11g
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