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This Vegetarian Breakfast Casserole is hearty, cheesy, and packed with colorful vegetables for the perfect meatless breakfast. Loaded with eggs, bread cubes, melty cheese, and savory veggies, it’s an easy vegetarian breakfast casserole that’s filling enough for brunch, holidays, or meal prep throughout the week.
Breakfast casseroles are some of the most popular recipes on All Things Mamma! Be sure to try my classic Easy Breakfast Casserole and Crescent Roll Breakfast Casserole too.
Why you’ll love this meatless breakfast casserole recipe!
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, sneaking veggies past picky eaters, or when you want a break from indulgent favorites like million dollar bacon.
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!
- Perfect Make-Ahead Breakfast: Assemble it the night before and simply bake in the morning.
- Loaded With Vegetables: This casserole is packed with mushrooms, peppers, broccoli, onions, and tomatoes for tons of flavor and nutrition.
- Hearty and Filling: Eggs, bread cubes, and cheese make this meatless breakfast casserole satisfying enough to keep everyone full.
- Easy to Customize: Swap in your favorite vegetables, cheeses, or add meat if desired.
- Great for Feeding a Crowd: Perfect for holidays, brunches, or busy mornings with the family.
Table of Contents
Ingredient Notes
See recipe card below this post for ingredient quantities and full instructions.
- Large eggs – The base of the casserole.
- Whole milk – Helps create a rich, creamy texture.
- 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. (For a breakfast casserole with a different base, try this Crescent Roll Breakfast Casserole!)
- 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).
Variations
- 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 oven-cooked 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
- 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.
- 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.
- 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.
- Bake: Bake the casserole for 40 minutes. The top of the casserole should be golden and puffed up. Serve while hot!
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!
How to Store
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.
Frequently Asked Questions
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!
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.
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
Breakfast Casseroles
Overnight Baked French Toast Casserole
Breakfast Casseroles
Crescent Roll Breakfast Casserole
Breakfast Casseroles
Sausage, Egg, and Cheese Breakfast Casserole With Bread
Breakfast Casseroles
Farmer’s Breakfast Casserole
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Vegetarian Breakfast Casserole
Equipment
- 1 Mixing bowl
- 1 9×13 baking dish
- 1 large skillet
Ingredients
- 10 eggs
- 3 cups whole milk
- 1 teaspoon salt
- ½ teaspoon ground black pepper
- ⅛ 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
Instructions
- 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.
Video
Notes
- Let the bread soak fully: This helps create a soft, custardy texture instead of dry bread pieces.
- Don’t skip the resting time: Let the casserole sit for 5–10 minutes after baking so it slices more easily.
- Make it ahead: Assemble the casserole the night before for an even easier morning.
- Cover loosely if browning too quickly: Tent foil over the casserole if the top starts getting too dark before the center finishes baking.
So hearty and satisfying 🧀 Love that it’s veggie packed and perfect for meal prep!
I tried this and it turned out so good. So hearty, cheesy, and perfect to prep ahead for the week.
This recipe was so easy to follow and turned out perfectly. Definitely making it again!