Name: Sourdough Breakfast Casserole with Kale
Prep time: 20 min
Cook time: 50 min
Total time: 90 min
Ingredients: 1 tablespoon extra virgin olive oil; 1 medium shallot (diced); 6 cups kale (about 1 bunch, stems removed and chopped; can use any type of kale); 4 cups sourdough bread (cubed or roughly torn); ½ cup shredded gruyere cheese (plus more for topping); 1 cup shredded sharp cheddar cheese (plus more for topping); 10 eggs; 2 cups milk; 2 tablespoons whole grain Dijon mustard; ½ teaspoon salt (more to taste); ¼ teaspoon freshly ground black pepper (more to taste)

Ingredients and Substitutions

Sourdough bread: This is the main ingredient, so try to get a good loaf from a bakery if you can. You can also use white bread or another kind of bread that you like, but it tastes best with sourdough in my opinion.

Kale: You can use any kind of kale, curly or lacinato (dinosaur). I’ve used both kinds and like it any way it’s made! Sub spinach if you don’t want kale.

Shallots: Sub red or yellow onion if that’s what you have.

Gruyere and sharp cheddar cheese: If you can’t find gruyere, substitute a Swiss cheese (like baby Swiss). You can also mix up the cheeses and try gouda, parmesan, or other favorites.

Whole grain Dijon mustard: Any kind of whole grain or stone ground mustard would probably work really well in sourdough breakfast casserole. I use the whole grain Dijon mustard from Trader Joe’s, but you can substitute regular Dijon if you want.

Milk: I have made it with skim and whole milk. Both work well. Even non-dairy milk would work.

Salt and pepper

Instructions

The full recipe for sourdough breakfast casserole, including ingredient quantities, is at the bottom of the post. Here’s a preview of the steps with photos to guide you in the kitchen.

diced shallots and chopped kale on a cutting board next to chef's knife

Prep the veggies. Dice the shallot and chop the kale.

kale and shallots cooking in olive oil in a skillet on a stove

Cook the kale and shallots in a skillet with some olive oil.

cooked kale and shallots in the bottom of a baking dish

Transfer the cooked kale and shallots to a greased baking dish.

torn sourdough bread cubes on top of cooked kale in a baking dish

Add sourdough bread pieces on top of the kale.

shredded cheese on top of bread and kale in a baking dish

Sprinkle with the shredded cheeses.

whisked eggs with milk, mustard, salt, and pepper in a mixing bowl

In a large mixing bowl, whisk together the eggs, milk, salt and pepper, and mustard.

ingredients for breakfast casserole prepared in a dish before being baked

Pour the egg mixture over the other casserole ingredients. Use a large spoon or fork to gently mix the ingredients to spread out the kale a little. Cover with foil and put in the fridge for at least 20 minutes.

sourdough breakfast casserole with kale after coming out of the oven

Bake covered with foil for about 30 minutes. Uncover and bake for another 15 minutes until the bread is slightly browned.

Make Ahead Instructions

Sourdough breakfast casserole can easily be made in advance and stored in the refrigerator for up to 12 hours before baking. Prep it the night before, cover with foil, put it in the fridge, and simply transfer it to the oven when you wake up the next morning. However, you don’t need to let it sit overnight (20 minutes will do) if you would rather make the recipe all in one morning!

Storage and Reheating

Keep leftover pieces in an airtight container in the refrigerator for up to 3 days. Reheat in the microwave for 1-minute intervals until warmed through.

a slice of Sourdough Breakfast Strata with Kale on a white plate next to the dish

Serving

I love serving this easy sourdough breakfast casserole as part of a brunch spread with fresh fruit or juice, muffins, and other favorites. It would taste great with my Prosecco and Carrot Juice Cocktails and Oatmeal Orange Carrot Muffins with Cranberries. Explore my full breakfast category for more ideas.

📖 Recipe