Breakfast Casserole with Butternut Squash and Kale

This breakfast casserole is the perfect fall dish. Earthy sage balances butternut squash between layers of crusty bread, eggs, kale, and cheese. Assemble it the night before and bake the next day to serve for breakfast, brunch, lunch, or dinner.

By
Rachael Narins
Rachael Narins
Rachael Narins
Rachael authored best selling cookbook Cast-Iron Cooking, is a professionally trained chef, and has been writing professionally for more than 10 years.
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Updated July 03, 2022
Rachael Narins
Fall Breakfast Casserole cut into slices and stacked on a white plate. Sage and the rest of the casserole dish are behind the plate.
Rachael Narins

Breakfast casserole, also known as strata, is a baked egg dish in the same family as bread pudding, but savory. You can assemble it the night before and bake it the next day for breakfast, brunch, a casual dinner, or a fantastic holiday side dish.

For this recipe, toasted pieces of bread are soaked in a sage and garlic egg-milk mixture and layered between cubes of roasted butternut squash, kale, and cheese. The resulting dish is rich and filling.

Using turmeric brightens up the whole affair, but you can leave it out if you don’t have any on hand. There is a lot of beta carotene in there, so it will be gorgeous either way. A sunny-looking meal for the chilly, shorter days of fall and winter.

Tips, Trade-Outs, and Ideas

Breakfast casseroles are easy to adapt to personal preferences and what you have on hand. My version is vegetarian and full of fall flavors, but you can swap out some ingredients and add in others to make it your own. Here are a few ideas.

  • Once it has been baked and cooled, pan fry the slices of strata with lots of butter. It’s like a grilled cheese sandwich with so much more to love!
  • Add two cups of cooked and crumbled chicken, sausage, or vegetarian sausage to the kale layer.
  • Try a Southwestern spin—add diced and roasted green chili peppers instead of kale, and use Pepper Jack cheese. Sprinkle a little ancho chili powder or paprika on top before baking.
  • Change the herbs to rosemary, oregano, thyme, fennel seed, or coriander. Just keep the amount two tablespoons.
  • Include a big pinch of chili flakes to spice things up.
  • If you really want to go wild, make it as a holiday side dish and serve it with some warm turkey gravy or a crimson pool of cranberry sauce. It’s already half a Thanksgiving meal anyway.
Fall Breakfast Casserole with a sprig of fresh sage on top.
Rachael Narins

Carb Questions! What Bread Works Best?

For this breakfast casserole, I used half a loaf each of sliced sourdough and whole wheat bread from Manhattan Beach Bagel. You can really toast ANY type of savory bread to change things up or mix and match. It’s a super flexible recipe.

  • White sandwich bread
  • Baguette
  • Ciabatta
  • Challah
  • Brioche
  • Rye
  • Pumpernickel
  • Italian
  • Toasted cornbread would even be a head-turning option

What Is the Best Cheese for Breakfast Casseroles?

I used the very convenient pre-shredded Swiss from my local grocery store and then grated up all the bits and ends I had in the fridge to make it a full cup. That included Monterey Jack, Provolone, and (I confess) a little piece of what I think was Manchego.

As long as the cheese is good, it will work in the center layer. Even some dollops of goat cheese, cream cheese, or ricotta would be delicious. Try to keep it at one cup total and let your creativity flow. Non-dairy cheese works too if you want to stay non-dairy.

No Kale, No Problem

If you want to include a bit of green, but kale isn’t your thing, try defrosted and very thoroughly squeezed frozen spinach .

Still not your jam? How about chopped green scallions or some peeled and shredded kohlrabi? Mmmmm. Kohlrabi for the win!

Side view of the layers of a Pumpkin Sage Strata on a white plate with a casserole dish, cheese wedges and sage behind it.
Rachael Narins

Different Ways to Cook Egg Casseroles

I’ve made this recipe in one large casserole dish to make it easy, but if you want to dress it up a bit make individual servings.

  • Make it fancy: Divide the bread into buttered 8-ounce ramekins, 4-ounce mason jars (you’ll need 16 of them) or short, oven-safe coffee cups. The single-serving size will make the dish even more special, and it cuts the cooking time by about 12 minutes.
  • Make it rustic: Bake this butternut squash casserole in a 12-inch cast-iron skillet. The exterior will get a bit crispier, which adds an extra layer of texture and flavor.
  • Slow Cooker Casserole: This absolutely works in a slow cooker and an Instant Pot. How great is that? The results will be softer, but it’s an excellent solution if you need the oven space for something else. Put everything except the Parmesan in the slow cooker or Instant Pot bowl overnight. Right before cooking, top with Parmesan and set it to medium for 2 to 3 1/2 hours for a slow cooker and 12 minutes for an Instant Pot.

Make Breakfast Casserole Ahead of Time

Breakfast casseroles are an easy make ahead meal. Just assemble the recipe the night before. Cover and keep it in the fridge. The next morning, bake it according to the recipe instructions.

More Cozy, Savory Breakfast Casseroles!

Breakfast Casserole with Butternut Squash and Kale

Prep Time 40 mins
Cook Time 45 mins
Total Time 85 mins
Servings 10 to 12 servings

Ingredients

  • 16 ounces (12 cups) sourdough bread

  • 3 tablespoons olive oil

  • 2 teaspoons garlic powder

  • 2 teaspoons dried ground sage

  • 1/2 teaspoon black pepper, more to taste

  • 6 large eggs

  • 2 1/2 cups whole milk

  • 1 (15-ounce) can pumpkin puree

  • 1 teaspoon turmeric (optional)

  • 1 teaspoon salt

  • 1 pound butternut squash, peeled and diced into 1/2-inch cubes

  • 1 bunch (2 cups shredded) kale

  • 1 cup Swiss cheese, shredded

  • 1/2 cup Parmesan cheese, grated

  • Fresh sage leaves, for garnish (optional)

Method

  1. Preheat the oven and prepare your baking sheets and casserole dish:

    Preheat your oven to 400°F and line two sheet pans with foil, and lightly grease your 9x13 baking dish.

  2. Prep the bread:

    Tear or cut the bread into bite-size pieces and arrange in a mostly single layer on the sheet pans. Lightly coat the pieces of bread with olive oil, then season evenly with garlic powder, dried ground sage, and black pepper. The oil will help it stick.

  3. Toast the bread:

    Place the baking sheets in the oven, and toast until the bread is golden brown, with some dry edges, about 5 minutes. There is no need to rotate the pans or toss the bread cubes.

    Torn bread on baking sheets to make Pumpkin Sage Strata.
    Rachael Narins
  4. Whisk your custard:

    While the bread is toasting, in a large bowl whisk together the eggs, milk, pumpkin puree, turmeric (if using), and salt.

  5. Remove the bread and let it cool:

    Once the bread is toasted, remove it from the oven, and let it cool for 5 minutes. Once the toasted bread has cooled, add 1/2 of it to the egg mixture, stirring to coat. The bread will collapse slightly, then you can then add the rest, stirring to coat.

    Set that aside to soak. It won’t be out too long, so you don’t need to worry about covering it.

  6. Bake the squash:

    Add the diced butternut squash to the same foil-lined pan you toasted the bread on and place on the center rack of your oven. Let it roast for 22 minutes, or until golden and tender.

    Remove the squash from the oven to cool slightly and assemble the strata.

    Cubes of slightly roasted butternut squash to make a Savory Pumpkin Egg Bake.
    Rachael Narins
  7. Assemble the dish:

    Into the 9x13 baking dish, add half the soaked bread and press it down into the dish. Add the roasted butternut squash in a nice even layer, then the kale. Next, add the shredded cheese. Top that with the remaining soaked bread and any liquid in the bowl, pressing that down gently. Sprinkle grated Parmesan cheese evenly over the top. Cover the whole dish with a sheet of foil.

    You can refrigerate or freeze the strata at this point and bake it the following day or bake it right away.

    Overhead view of a Pumpkin Sage Strata in a casserole dish.
    Rachael Narins
    Grated cheese sprinkled over a Savory Pumpkin Egg Bake.
    Rachael Narins
  8. Bake the casserole:

    Place the casserole on a baking sheet, then place in the oven and bake for 25 minutes. Remove the foil and continue to bake for 20 more minutes, until the top is crispy and golden.

    Serve: When the strata is finished baking, let it cool on the counter for up to 30 minutes, then cut into squares and serve warm or at room temperature.

    Leftovers! After it’s cooled, wrap and refrigerate the casserole for up to three days.

Nutrition Facts (per serving)
300 Calories
12g Fat
34g Carbs
14g Protein
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Nutrition Facts
Servings: 10 to 12
Amount per serving
Calories 300
% Daily Value*
Total Fat 12g 16%
Saturated Fat 5g 24%
Cholesterol 110mg 37%
Sodium 580mg 25%
Total Carbohydrate 34g 13%
Dietary Fiber 4g 13%
Total Sugars 7g
Protein 14g
Vitamin C 16mg 81%
Calcium 244mg 19%
Iron 3mg 18%
Potassium 410mg 9%
*The % Daily Value (DV) tells you how much a nutrient in a food serving contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.
Nutrition information is calculated using an ingredient database and should be considered an estimate. In cases where multiple ingredient alternatives are given, the first listed is calculated for nutrition. Garnishes and optional ingredients are not included.