This Vegetarian Breakfast Casserole with egg is LOADED up with all the colorful mixed veggies: sweet potatoes, broccoli, bell peppers, and more! It’s a great option for breakfast meal prep—leftovers are quick and easy to reheat. Unlike a lot of breakfast casseroles, this recipe doesn’t use hash browns!

A dish of vegetarian breakfast casserole on the table with a slice on a plate in the background.

Breakfast is supposed to be the most important meal of the day, right? Well, I personally think all the meals are equally important (I couldn’t possibly play favorites), but I do believe that starting out the morning with a veggie-loaded breakfast recipe can really set the tone for an overall great day. 

Personally, I have found that a savory breakfast full of protein + veggies is the magical way to start the day (Try my Broccoli and Egg Breakfast Bake). I started the day feeling fueled, satisfied, and on a veggie-loaded foot.

This Vegetarian Breakfast Casserole is one of my favorite savory veggie packed breakfasts to make ahead of time. It’s loaded with colorful veggies (sweet potatoes, broccoli, bell peppers, tomatoes) and protein from eggs. The addition of pesto to this veggie breakfast casserole brings it next level in the flavor department. Since this recipe makes 10 servings, it is great to make for a crowd. Or, I love to make it during my weekly meal prep, store it in the fridge, and reheat a slice each morning in the oven or air-fryer. It is naturally gluten free along with being vegetarian, but you can make it dairy-free with a few small modifications.

Process shot for how to make vegetarian breakfast casserole.

Suggested adaptations

Use different vegetables. There are so many vegetables that would work well in this Vegetable Breakfast Casserole. You can use zucchini, cauliflower, greens like spinach or kale, peas, etc. Frozen vegetable will also work well, just make sure whatever vegetable you use in this recipe is mostly cooked through before you add the egg mixture on top.
 
Don’t like or have sweet potato? Regular potato varieties, such as Yukon Gold, would work well in this recipe, too.
 
Add cheese! Stir in about a cup of shredded mozzarella or cheddar or diced fresh mozzarella to the egg mixture to give the dish lots of extra yummy flavor.
 
Make it dairy-free. Be sure to use or make a dairy-free pesto (Trader Joe’s carries a good one!) and use an unsweetened, unflavored dairy-free milk.

Vegetarian not needed? Adding some cooked bacon or cooked breakfast sausage to this breakfast casserole would add wonderful flavor!

Want to find out the BEST way to cut bell peppers? Head over to my How To Cut a Bell Pepper…to minimize waste! post!

A slice of vegetarian breakfast casserole on a plate with a fork. The rest of the casserole is next to the plate.

How to store and reheat this breakfast casserole

This veggie breakfast casserole is great to make ahead and keep in the fridge for a veggie-packed breakfast or quick meal any time of day. It will keep, well covered, in the refrigerator for 4 to 5 days.

I like to just cover the whole baking dish with foil for easy storage and then pop it into an oven at 350℉ to warm up for about 15 minutes. I keep foil on to prevent extra browning of the eggs.

If you prefer to reheat by the slice, you can use a toaster oven or pop a piece into a microwave to warm up on half power for about 30 seconds.

Other veggie-loaded breakfast recipes you will love

Did you try this Vegetarian Breakfast Casserole and now you’re hungry for more? 

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A slice of vegetarian breakfast casserole on a plate with a fork and strawberries.
5 from 5 votes

Rainbow Veggie Breakfast Casserole

Yield: 10 servings
Prep Time: 10 minutes
Cook Time: 45 minutes
Cuisine: American
Course: Breakfast, Main Course
This Vegetarian Breakfast Casserole with egg is LOADED up with all the colorful mixed veggies: sweet potatoes, broccoli, bell peppers, and more! It’s a great option for breakfast meal prep—leftovers are quick and easy to reheat. Unlike a lot of breakfast casseroles, this recipe doesn’t use hash browns!

Ingredients
 

  • 3 teaspoons olive oil or avocado oil, divided
  • 1 large sweet potato, washed and cut into ½-inch dice
  • 1 teaspoon salt, divided and to taste
  • black pepper, to taste
  • 2 cups small broccoli florets
  • 1 bell pepper, cut into ½-inch dice
  • 10 large eggs
  • cup milk of choice
  • ¼ cup pesto , store-bought or homemade pesto, dairy-free if desired
  • 4 small tomatoes, such as Roma or on-the-vine
  • ¼ cup snipped chives or sliced green onions

Instructions
 

  • Preheat oven to 425℉. Grease a large baking dish (9-by-13 inch) with a teaspoon of oil (or use oil spray if you prefer).
  • Place diced sweet potatoes in the baking dish. Drizzle with a teaspoon of oil and sprinkle with a pinch of salt and a few grinds of black pepper. Toss to coat, then spread into an even layer. Roast until the potatoes start to soften and brown, about 15 minutes.
  • Toss the broccoli and peppers with the remaining teaspoon of oil and season with salt and pepper. Scatter the broccoli and peppers over the partially cooked sweet potatoes, then continue to roast. Cook until the broccoli tops begin to brown, about 10 minutes.
  • Meanwhile, in a large bowl, whisk together the eggs, milk, and pesto. Season with a pinch of salt and a few grinds of black pepper. Cut tomatoes crosswise into 4 to 5 slices and set aside.
  • Once vegetables are browned, remove the pan from the oven. Reduce the oven temperature to 350℉.
  • Whisk the egg mixture again to make sure everything is well combined then pour it over the vegetables. Place sliced tomatoes over the top of pan in rows, then scatter with half of the chives or green onions.
  • Bake until cooked through and the center of the casserole is firm, 20 to 25 minutes.
  • Allow to cool for 5 to 10 minutes, sprinkle with remaining chives/green onions, then slice into squares. Serve warm or at room temperature. Store leftovers in fridge for up to 4 days.
Calories: 156kcal, Carbohydrates: 12g, Protein: 8g, Fat: 9g, Saturated Fat: 2g, Trans Fat: 1g, Cholesterol: 187mg, Sodium: 392mg, Potassium: 371mg, Fiber: 2g, Sugar: 4g, Vitamin A: 6048IU, Vitamin C: 38mg, Calcium: 73mg, Iron: 1mg
Nutritional information provided here is only an estimate shared for convenience and as a courtesy. Information will vary based on ingredients + brands used to create the recipe.