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vegetarian breakfast casserole strata with swiss chard on a blue plate

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


  • 1 tablespoon 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 tablespoon smooth dijon mustard
  • cups milk
  • 1 teaspoon 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