Vegetarian Breakfast Casserole with Swiss Chard and Gruyere

Swiss Chard and Gruyere Strata is a make-ahead vegetarian breakfast casserole that’s perfect for feeding a crowd. Loaded with veggies, eggs, cheese, and crusty bread, this breakfast bake soaks overnight in your fridge and bakes up in the morning. Leftovers freeze like a dream, and this is also a fantastic packed lunch. 

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overhead photo of a vegetarian breakfast casserole on two plates

I get up early, but I’ve never considered myself a morning person. 

I used to get up very, very early because my job required it. Then, because it was a way to get a quiet hour to myself before my kids woke up. But now days I get up early because my second born is an obnoxiously early riser and I really have no choice. 

Because I have my hands full pretty much from the moment I open my eyes these days, I’ve had to become a master of make-ahead breakfast recipes, (I’ve got a list of 16 Vegetarian Breakfast Recipes you can make ahead, if you’re interested), otherwise we’d all be eating cold cereal day after day and that is not only not comforting in the slightest, but it’s booooooring. 

Today I want to share with you one of my favourite things to make for breakfast, packed lunches, or even dinners if breakfast-for-dinner is your kind of thing.

Have you ever made strata before? This vegetarian breakfast casserole is made of delicious layers of crusty bread, cheese, and veggies, and then soaked overnight with an eggy custard that’s poured over the top. 

Come morning time all you need to do is open your eyes enough to be able to operate your oven, and sling your casserole in there to bake while you drink your Matcha Latte, or whatever gets your brain fully powered, while your kitchen starts to smell absolutely delightful. About 45 minutes later you’ll have a puffed, golden, gloriously cheesy breakfast casserole that also happens to be loaded with veggies. 

Shall we make some? I’ll show you how!

eggs, bread, milk, cheese, swiss chard, onion, and mustard on a grey background

What’s in this vegetarian breakfast casserole?

Feel free to check off the ingredients you need in the printable recipe card at the bottom of this post. In the mean time, here’s what you need:

  • Bread –> A nice loaf of crusty bread, preferably a bit stale. 
  • Eggs –> We’re using nine large eggs in this recipe.
  • Milk –> I used whole milk, but whatever you’ve got is fine.
  • Swiss chard –> Or another green, like spinach or kale.
  • Onion –> A medium-sized guy to bring the flavour.
  • Gruyere cheese –> Yes please.
  • Parmesan –> Or another vegetarian-friendly hard cheese of your choice.
  • Mustard –> Taking a trip to flavour town with smooth Dijon mustard.
  • Salt and pepper –> As one does. 

Do I need any special equipment to make this recipe?

You’ll need a nice big casserole dish large enough to hold everything. The one pictured here is this 9×12 inch rectangular casserole dish from Le Creuset. 

You will also need a large frying pan or skillet to cook the greens. I used my favourite non-stick frying pan for this. 

swiss chard and onions in a non-stick frying pan

How do you make a breakfast strata recipe?

Get organized by cubing your bread, grating your cheese, and chopping your veggies.

Step 1: Heat a bit of olive oil in a large frying pan. Add the onions, and fry until translucent. Then, add the swiss chard and sauté, stirring frequently, until the greens are wilted but the stems still have a bit of crunch. 

Remove from the heat and set aside to cool slightly.

Step 2: Combine the eggs, milk, mustard, salt, and pepper in a large bowl and whisk until smooth. I love this 8-cup Pyrex measuring cup because it’s big enough to mix in and easy to pour from. 

eggs being mixed with milk in a pyrex bowl

Step 3: Generously butter a large rectangular casserole dish. Scatter 1/3 of the cubed bread over the bottom. It won’t fully cover the bottom (see photo below) but that’s ok. 

Step 4: Scatter 1/3 of the swiss chard mixture over the bread. 

photo collage of bread and swiss chard being layered into a casserole dish

Step 5: Scatter 1/3 of the cheeses over top of the swiss chard mixture. 

Repeat steps 3-5 two more times, until you’ve layered all of the ingredients into your casserole dish. 

photo collage of a vegetarian breakfast casserole being made

Step 6: Pour the egg custard over the bread, cheese, and vegetables. 

egg custard being poured over a vegetarian breakfast casserole

Step 7: Cover the casserole dish (I use Bee’s Wrap as a sustainable option) and place it in the fridge. 

Your strata needs to soak in the fridge for at least four hours, but up to 24 hours. 

photo collage of an overnight vegetarian breakfast casserole

Step 8: Good morning! It’s time to bake this thing! Fire on your oven, and sling the casserole in there. Don’t forget to remove the Bee’s Wrap or plastic wrap first. 

The strata will bake for 45-55 minutes, and is done when it’s puffed, golden, and only slightly jiggly in the middle. When it’s finished baking, let it rest for about 10 minutes before serving. 

Then you can serve warm scoops of bready, cheesy, comforting goodness onto waiting plates and dig in!

Here’s why I love this vegetarian breakfast casserole:

  • It’s a perfect make-ahead dish, whether you’re making it for a lazy weekend brunch or to tuck into the freezer for easy lunches or dinners.
  • It’s loaded with protein! There are 9 eggs in this dish, plus nearly a liter of milk, plus a good amount of cheese.
  • It’s an excellent vehicle for sneaky vegetables.
  • It’s warm and comforting and all kinds of delicious.

Trust me, you’re gonna love it!

overhead photo of a vegetarian breakfast casserole in a white casserole dish

How far in advance can I make this strata recipe?

You need to soak the casserole for at least four hours, but you can leave it in the fridge for up to 24 hours. 

How should I store leftover breakfast casserole?

Cooled strata can be sliced into squares, wrapped in foil, and frozen for quick and easy meals. They make for a great packed lunch.

Does my bread need to be stale?

The staler your bread, the better the casserole will be. If you use a very fresh loaf of bread the strata can turn out kinda gooey in the middle, so recommend a nice crusty loaf that’s been left lying around for a day or two. 

This is a great way to use up old bread, and you could even get a deal on day old bread from your local bakery. 

Can I use a different kind of green?

Sure thing. If you don’t have swiss chard you can use spinach, kale, or collard greens instead. 

Can this casserole be made gluten-free?

I have not personally tried this, but I assume you can use a loaf of gluten-free bread for the same results. If you’re looking for Low FODMAP Breakfast Recipes, check this guide for inspiration. 

Can this casserole be made vegan?

There’s way too much cheese and milk and eggs to talk substitutions here. But if you’re looking for a vegan breakfast casserole, I recommend you check out this Vegan Strata from Veganosity

What’s the deal with Swiss chard?

 Swiss chard is  a leafy green vegetable that belongs to the same family as beets, spinach and quinoa – the chenopod family. Rich in phytonutrients, chard provides a host of antioxidant and anti-inflammatory benefits.

It’s an excellent source of vitamin C, E, beta-carotene (a precursor to vitamin A) manganese and zinc. It’s also a good source of bone-healthy calcium and vitamin K, as well as potassium, vitamin E, and iron.

Rich in dietary fiber and with a good amount of protein, chard works to moderate the passage of food through the digestive tract and stabilize blood sugar.

vegetarian breakfast casserole on white and blue plates with a white casserole dish in the background

Other tasty recipes you might enjoy:

Spiced Sweet Potato Waffles
Maple Apple Granola
Roasted Vegetable Frittata
Whole Wheat Muffins with Cinnamon Roasted Apples

vegetarian breakfast casserole strata with swiss chard on a blue plate
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4.75 from 4 votes

Vegetarian Breakfast Casserole with Swiss Chard and Gruyere

Swiss Chard and Gruyere Strata is a make-ahead vegetarian breakfast casserole that's perfect for feeding a crowd. Loaded with veggies, eggs, cheese, and crusty bread, this breakfast bake soaks overnight in your fridge and bakes up in the morning. Leftovers freeze like a dream, and this is also a fantastic packed lunch.
Course Breakfast
Cuisine American
Keyword Breakfast casserole, Strata
Prep Time 20 minutes
Cook Time 55 minutes
Total Time 1 hour 15 minutes
Servings 8
Calories 438kcal
Author Katie Trant


  • 1 Tbsp extra virgin olive oil
  • 1 medium yellow onion diced
  • 1 large bunch Swiss chard washed and roughly chopped
  • 8 cups cubed whole grain bread in one-inch cubes I used a sourdough rye
  • 2 cups coarsely grated gruyere
  • 1 cup finely grated Parmesan cheese
  • 9 large eggs
  • 2 Tbsp smooth dijon mustard
  • cups milk
  • 1 tsp salt
  • freshly ground black pepper


  • Heat olive oil in a large skillet over medium-high heat.
  • Add the onion, and sauté for about 3 minutes, until translucent.
  • Add the Swiss chard, and sauté until wilted and the stems are slightly browned. Season with salt and pepper and remove from the heat.
  • Generously butter a 9x13 casserole dish.
  • Layer one-third of the bread cubes over the bottom of the dish. It won't fully cover the bottom, but this is ok.
  • Layer one-third of the sautéd chard over top of the bread, followed by one-third of the gruyere, and one-third of the Parmesan.
  • Repeat these layers two more times.
  • Whisk eggs together with Dijon mustard, then whisk in the milk, salt, and pepper.
  • Pour the custard over top of the strata layers. Cover with plastic wrap, and set in the fridge overnight or for at least four hours, but up to one day.
  • When you're ready to bake, preheat the oven to 350°F /180°C.
  • Bake the strata for 45-55 minutes, until it is puffed and golden on top, and no longer so jiggly in the middle (a little jiggle is ok as it will continue to cook as it cools).
  • Remove from the oven and let stand for 10 minutes before serving.


  • If you don't have Swiss chard you can substitute another sturdy leafy green, such as kale, collard greens, or mustard greens.
  • Any sharp cheese can be used in place of the gruyere, but it really is delicious.
  • I don't have a lot of fridge space, so I often just soak on the counter for an hour before baking. This is totally fine.
  • Cooled strata can be sliced into squares, wrapped in foil, and frozen for quick and easy meals. They make for a great packed lunch.
  • Nutrition values are an estimate only.


Calories: 438kcal | Carbohydrates: 23g | Protein: 29g | Fat: 25g | Saturated Fat: 12g | Cholesterol: 293mg | Sodium: 919mg | Potassium: 325mg | Fiber: 1g | Sugar: 6g | Vitamin A: 1268IU | Vitamin C: 3mg | Calcium: 623mg | Iron: 3mg


This recipe was originally published September 25, 2015. It was retested, rephotographed, and updated on December 29, 2019.


  1. Emily says

    Made this for dinner this week and it’s doing double duty for lunchtime leftovers. My 9 month old baby gobbled it up too. Winner!

  2. Julia says

    Hi Katie, When this dish gets wrapped in foil and frozen to defrost can it travel for example to work in the foil, defrosting slowly, then put in fridge until lunch when it then I assume gets put in a low temperature oven to heat up? Thanks for the recipe!

    • Katie Trant says

      Hi Julia! When I take it to work for lunch I just throw it in my bag frozen, still wrapped in the foil. I keep it by my desk at work and by lunch time it’s usually still slightly frozen, so then I remove the foil and heat for a few minutes in the microwave. You could also defrost it overnight in your fridge, keep it in the fridge at work, and then reheat. Reheating in a low-temp oven would also work, but at my office all there is are microwaves, so that’s what I use.

  3. Anne T. says

    Katie, thank you for posting this recipe. I made it tonight, and the taste and texture are amazing. I used rye bread, too, and that definitely enhances the other flavors. It literally melts in your mouth, and I love the fact that I now have dinner for two for four more nights!

    So glad you’re back, and congratulations on Baby Muffin Myth 🙂

  4. Joyce says

    Sounds delicious, and have loads of rainbow chard in garden. But I’m gluten intolerant. In a vaguely similar eggs and cheese dish I’ve replaces bread with rice flakes. Do you think that would work here?


  1. […] Swiss Chard and Gruyere Strata // This make ahead breakfast-for-dinner will leave you satisfied — and with plenty of leftovers to enjoy over the weekend! […]

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