This veggie breakfast casserole with tons of sautéed spinach, onions, and bell peppers keeps you full for hours! The vegetarian breakfast recipe is perfect for a crowd, too. It’s easy. It’s adaptable. And it can be prepped overnight!
I love it because it’s easy to make, and I can make it ahead. I have everything ready a day before, so in the morning all I have to do is slide it in the oven. The family loves it because it’s hearty, flavorful, and simply delicious!
While we love a sweet start to the day with cinnamon bread pudding or French toast casserole, a fully loaded savory breakfast casserole like this is just what you need on a cold January morning.
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What Is Breakfast Casserole?
A breakfast casserole is a hearty, wholesome, comforting dish. The all-in-one recipe combines eggs, cheese, bread, and meats or vegetables. All of it is baked together in a casserole dish. It's delicious and versatile at the same time. Perfect for feeding a crowd or meal prepping for the week.
Why You’ll Love This Recipe?
It’s an easy crowd-sized breakfast recipe for vegetarians.
A great make-ahead recipe! Just assemble everything the night before and bake the next morning!
You can enjoy it on a weekday morning or a lazy Sunday.
Needs zero technique.
Very versatile with countless yummy mix-ins.
Veggie Breakfast Casserole Ingredients
Vegetables: Onions, spinach, and all three colors of bell peppers were my choices. You can use any fresh veggies you have in your fridge; just remember to sauté them before you add them to the casserole.
Bread: I wanted to make breakfast casserole with sourdough bread. But any crusty bread, like my no-knead Dutch oven bread or easy everyday bread, will do. The older, the better, as it absorbs the egg custard better.
Eggs bind the make-ahead veggie breakfast casserole. I used 8 large ones.
Milk: Whole milk is preferable, but you can use toned milk too to whisk the eggs.
Cheese: I love the flavor of rich, salty cheddar cheese. I shredded some and added it to the casserole.
Seasoning: I used Italian seasoning along with salt and pepper.
Variations
Like quiche, casseroles are very versatile. You can use any vegetables you have, like mushrooms, tomatoes, broccoli, kale, asparagus, or green beans. Just cook them, so the breakfast casserole is not soggy. Add finely minced garlic or even garlic confit, olives, and sun-dried tomatoes to enhance the flavor.
I kept my sourdough breakfast casserole vegetarian. You can turn it into a sausage egg breakfast casserole. Add any meat you please, such as ham, salami, or shredded chicken or pork.
You can replace the bread with cooked potatoes (roasted or pan-fried).
Don’t love cheddar? Goat cheese, mozzarella, Emmental cheese, or even Monterey Jack will do. Feta is a fabulous addition here too as spinach and feta cheese are a great combo like in my feta and spincha muffins!
How To Make Breakfast Casserole With Veggies?
Step 1: Heat olive oil in a saucepan. Add onions and saute for 2-3 minutes. Then add the chopped bell peppers, Italian seasoning, salt, and pepper. Cook for 3-4 minutes, until softened.
Step 2: Add chopped spinach to the cooked veggies. Cook until just wilted. Remove from heat.
Step 3: Lightly grease a baking dish and place the bread cubes at the bottom of the dish.
Step 4: Spoon the cooked vegetables on top of the bread.
Step 5: In a medium bowl, whisk together the eggs, milk, and cheese. Lightly season the mixture with salt and pepper.
Step 6: Pour on top of the bread and vegetable mixture. Cover and refrigerate for at least 1 hour or up to 24 hours.
Step 7: Preheat your oven to 190 C / 375 F when you're ready to bake. Uncover the casserole and bake for 40-45 minutes until the top is golden and puffy and a skewer inserted in the center comes out clean.
Let the casserole rest for 15- 20 minutes before slicing and serving!
Pro Tips
- Cook the veggies. You don’t want a watery sourdough bread breakfast casserole.
- If using frozen spinach, thaw it and drain it well before using.
- After assembling the egg veggie casserole, let it rest in the fridge for at least an hour, so the flavors can mingle. You can leave it for up to a day.
- Season the casserole at each step. Season the veggies as you cook them. I also recommend seasoning the egg mixture.
- The casserole will be puffy when it is baked through because of the eggs. But it will deflate as it cools.
How To Store
You can refrigerate breakfast casserole with veggies covered for up to 3 days. Reheat in a preheated oven for 5-6 minutes or a microwave.
Vegetarian Breakfast Casserole FAQs
Don’t have old bread lying around? Cut fresh bread into cubes and bake for 10 minutes. When the cubes are crisp, they’re ready to soak up the egg custard.
Yes, you can. Make sure you thaw it and drain it well before using.
This casserole is amazing as-is. A dash of gochujang mayo, homemade chili oil, or pistachio pesto will really amp up the flavors. A side of fresh fruits will give the hearty casserole a light companion. Or you can add hash browns or simple toasted bread.
Yes, you can. Wrap the unbaked casserole well in foil and freeze for up to a month.
You can even freeze the baked casserole. Thaw before you reheat it in an oven.
📖 Recipe
Veggie Breakfast Casserole
Ingredients
- 6-7 slices Sourdough bread, cut into cubes
- 1 tbsp Olive oil
- 1 small Onion, finely chopped
- 1 Red bell pepper, finely chopped
- 1 Yellow bell pepper, finely chopped
- 1 Green bell pepper, finely chopped
- 3.5 oz Spinach, chopped
- 1.5 tsp Italian seasoning
- Salt & Pepper to taste
- 8 Eggs
- 1/2 cup Milk
- 1 cup Shredded cheddar cheese
Instructions
- Lightly grease a 3-quart baking dish.
- Place the bread cubes at the bottom of the dish.
- Heat the olive oil in a large saucepan and add the chopped onions. Saute for 2-3 minutes on medium-high flame until translucent.
- Add the bell peppers, Italian seasoning, salt, and pepper, and cook for 4-5 minutes until the veggies soften.
- Add the spinach and cook until it's just wilted. Take the pan off the heat and transfer the veggies on top of the bread.
- In another bowl, whisk together the eggs, milk, and cheese with a pinch of salt and pepper.
- Pour on top of the bread and vegetable mixture. Cover and refrigerate for at least 1 hour or up to 24 hours.
- When you're ready to bake, take the casserole out of the fridge and preheat the oven to 190 C / 375 F.
- Bake, uncovered at 190 C/ 375 F for 40-45 minutes until the top is golden brown and a skewer inserted in the center comes out clean.
- Lett the casserole rest for 20 minutes before slicing and serving. Enjoy!
Video
Notes
- Cook the veggies. You don’t want a watery sourdough bread breakfast casserole.
- If using frozen spinach, thaw it and drain it well before using.
- After assembling the egg veggie casserole, let it rest in the fridge for at least an hour, so the flavors can mingle. You can leave it for up to a day.
- Season the casserole at each step. Season the veggies as you cook them. I also recommend seasoning the egg mixture.
- The casserole will be puffy when it is baked through because of the eggs. But it will deflate as it cools.
- This casserole keeps well in the refrigerator for up to 3 days. Reheat in the microwave or a preheated oven for 5-6 minutes.
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