This Vegetarian Breakfast Casserole is the best way to start the day! Full of vegetables and protein, it’s hearty, cheesy, and full of savory flavor. Prepare it in advance for easy meals throughout the week.

close up image of a wooden spatula digging into a serving of vegetarian breakfast casserole.

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Some days it’s just good to have a break from meat in every meal, right?! This vegetarian breakfast casserole is perfect for anyone following a vegetarian diet, looking for ways to disguise healthy veggies from those picky eaters, or when you feel like a break from the usual bacon and sausage!

This meatless breakfast casserole can easily be adapted by swapping out the vegetables used in this recipe for those you love the most. It’s also a breeze to make ahead of time and simply pop in the oven when you’re ready to eat. Plus, the delicious smell from this breakfast casserole baking is enough to get the entire family around the table in no time!

Speaking of breakfast casseroles, be sure to check out my Cheesy Egg and Potato Breakfast Casserole, Amish Breakfast Casserole, Bisquick Breakfast Casserole With Bacon, and Eggs Benedict Casserole, too!

close up image of a wooden spatula digging into a serving of vegetarian breakfast casserole.

Vegetarian Breakfast Casserole Recipe

Vegetarian Breakfast Casserole is a complete meal with a healthy balance of protein, carbs, and fats. In addition, it’s full of fiber, minerals, and vitamins thanks to the assortment of vegetables. The combination of soft bread cubes, slightly crunchy veggies, puffy eggs, and melted cheese is simply irresistible.

Enjoy this Veggie Egg Bake casserole as is or alongside fresh fruit or a breakfast smoothie for a restaurant-worthy meal.

ingredients to make vegetarian breakfast casserole.

Ingredients for Vegetarian Breakfast Casserole

See recipe card below this post for ingredient quantities and full instructions.

  • Large eggs
  • Whole milk
  • Seasoning – Salt, ground black pepper, and cayenne pepper (optional).
  • Unseasoned stuffing bread cubes – Adjust the seasoning in this recipe if you use seasoned stuffing bread cubes instead.
  • Cheese – Shredded sharp cheddar cheese and gruyère cheese.
  • Butter – Salted or unsalted depending on your preference and dietary needs.
  • Vegetables – Diced onion, diced bell pepper (green and red), sliced mushrooms, halved cherry tomatoes, and frozen broccoli florets (thawed).


  • If you aren’t a fan of any of the veggies listed in this recipe, simply swap them out for those you do enjoy. This could include shredded zucchini, cubed potatoes, cauliflower florets, spinach, corn, cubed carrots, and peas. There are so many options!
  • Include bacon pieces, chopped ham, or ground sausage for a meaty version of this breakfast casserole.
  • Make this casserole dairy-free by using plant-based or dairy-free milk. Then, omit the cheese, or use dairy-free cheese.
  • Use gluten-free bread cubes for a gluten-free breakfast casserole.

How to Make Vegetarian Breakfast Casserole

  1. Prepare: Preheat the oven, and grease a 9×13-inch baking pan with cooking spray. Set aside.
  2. Make the egg mixture: Whisk the eggs in a bowl until smooth. Then, whisk in the milk and seasoning. Add the bread cubes, and stir to coat and moisten them. Allow this mixture to sit for 20 minutes while the bread soaks up the liquid.
  3. Cook the veggies: While the bread soaks, add butter to a skillet. Once melted, cook the onions, mushrooms, and peppers on medium-high heat for 10 minutes, stirring occasionally. Stir in the broccoli, and cook for another 5 minutes to remove excess water. Remove the skillet from the heat and, mix in the tomatoes. Set the skillet aside.
  4. Assemble the casserole: Stir the veggies and 1/2 cup of both types of cheese into the soaked bread mixture. Spread this mixture evenly into the prepared pan, and top it with the remaining shredded cheese.
  5. Bake: Bake the casserole for 40 minutes. The top of the casserole should be golden and puffed up. Serve while hot!
serving of vegetarian breakfast casserole sitting on a stack of two plates.

Quick Tip

This vegetarian breakfast casserole can be assembled the night before and stored in the fridge, covered with foil or plastic wrap. Allow the uncooked casserole to sit at room temperature to warm up while the oven preheats. Then, bake as normal!

How to Store Vegetarian Breakfast Casserole

Store leftovers covered with plastic wrap or aluminum foil or in an airtight container in the fridge for up to three days. Or, freeze for up to three months. Thaw in the refrigerator overnight when you’re ready to serve.

Reheat your casserole in the oven at 350 degrees Fahrenheit until heated through. Or, warm individual portions in the microwave in 30-second increments until your desired temperature is reached.

Serving Suggestions

To keep this meal vegetarian, enjoy this comforting and hearty vegetarian breakfast casserole alongside these breakfast potatoes, a refreshing fruit salad, or a healthy green smoothie.

Otherwise, feel free to add some crispy oven-baked bacon and sausage balls to the breakfast table!


What’s the difference between a frittata and a breakfast casserole?

A frittata features an egg mixture that cooks in a skillet on the stove before being transferred to the oven to bake completely.

A breakfast casserole consists of an egg mixture that is poured into a casserole dish and baked in the oven. There is no need for cooking on the stovetop!

Why is my breakfast casserole soggy?

If your casserole turns out soggy, it’s likely because too much liquid was used. You want to coat the bread pieces completely, but they shouldn’t be swimming in the egg mixture! In addition, be sure to allow the oven to preheat properly, and bake until the cheese is melty and the bread is lightly golden.

How do you know when a breakfast casserole is done?

The casserole will be golden brown on the top and will be puffed up. The liquid mixture should be set, and the casserole should feel slightly firm to the touch.

More Breakfast Casserole Recipes

A wooden spoon lifting a scoop of vegetarian breakfast casserole.

Vegetarian Breakfast Casserole

This Vegetarian Breakfast Casserole is the best way to start the day! Full of vegetables and protein, it's hearty, cheesy, and full of savory flavor. Prepare it in advance for easy meals throughout the week.
No ratings yet
Course: Breakfast
Cuisine: American
Servings: 10 servings
Prep Time: 30 minutes
Cook Time: 40 minutes
Total Time: 1 hour 10 minutes


  • 1 Mixing bowl
  • 1 9×13 baking dish
  • 1 large skillet


  • 10 eggs
  • 3 cups whole milk
  • 1 teaspoon salt
  • ½ teaspoon ground black pepper
  • teaspoon cayenne pepper optional
  • 8 cups unseasoned stuffing bread cubes
  • ¼ cup butter
  • 1 medium onion diced
  • 1 green bell pepper diced
  • 1 red bell pepper diced
  • 1 cup sliced mushrooms
  • 10 ounces frozen broccoli florets thawed
  • 1 cup halved cherry tomatoes
  • 1 cup shredded sharp cheddar cheese
  • 1 cup shredded gruyere cheese


  • Add the eggs to a large mixing bowl and whisk.
    10 eggs
  • Whisk in the milk, salt, pepper and cayenne if using.
    3 cups whole milk, 1 teaspoon salt, ½ teaspoon ground black pepper, ⅛ teaspoon cayenne pepper
  • Add the stuffing bread cubes to the eggs mix and stir to moisten them evenly.
    8 cups unseasoned stuffing bread cubes
  • Let the mix sit for 20 minutes until the bread soaks up the milk.
  • Preheat the oven to 375ºF and spray a 9×13 baking pan with cooking spray. Set the pan aside.
  • While the bread is soaking, add the butter, onions, pepper and mushrooms to a large skillet and heat over medium high heat. Cook for about 10 minutes to soften the veggies, stirring occasionally.
    ¼ cup butter, 1 medium onion, 1 green bell pepper, 1 red bell pepper, 1 cup sliced mushrooms
  • Stir in the broccoli and cook for another 5 minutes to get the excess water out of the veggie.
    10 ounces frozen broccoli florets
  • Remove the skillet from the heat and stir in the sliced tomatoes. Set aside.
    1 cup halved cherry tomatoes
  • Stir in the veggies and ½ cup of cheddar cheese and ½ cup of gruyere cheese into the bread and egg mix.
    1 cup shredded sharp cheddar cheese, 1 cup shredded gruyere cheese
  • Pour the mix into the 9×13 pan and spread evenly across the bottom of the dish.
  • Sprinkle the remaining cheese over the top of the casserole.
  • Bake for 40 minutes. The top will be golden browned and puffed up. The eggs will be set and firm to the touch.
  • Serve the casserole while hot.


Serving: 1serving | Calories: 395kcal | Carbohydrates: 31g | Protein: 21g | Fat: 21g | Saturated Fat: 11g | Polyunsaturated Fat: 2g | Monounsaturated Fat: 6g | Trans Fat: 0.2g | Cholesterol: 210mg | Sodium: 752mg | Potassium: 473mg | Fiber: 3g | Sugar: 9g | Vitamin A: 1415IU | Vitamin C: 54mg | Calcium: 407mg | Iron: 3mg
Did you make this recipe?Mention @kasey_allthingsmamma or tag #allthingsmamma!

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About Kasey Schwartz

For over 15 years, Kasey Schwartz, the mastermind behind All Things Mamma, has been the ultimate go-to for mouthwatering family recipes. Her work has been featured on, Buzz Feed, Better Homes and Gardens, and more, making her your go-to mom next door for all things delicious and family-friendly.

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