Easy Vegetarian Breakfast Casserole

The vegetarian breakfast casserole is loaded with fluffy eggs, veggies, meatless sausage, hash browns and cheddar cheese. It's super quick & easy to make and is perfect for holidays and meal prep!

I make breakfast casserole every single year for Christmas morning but it's a great breakfast option all year round.

When I became a vegetarian in college, I threw my mom's annual Christmas sausage egg casserole for a bit of a loop. You mean... vegetarian breakfast casserole? Yep.

After a few years of experimenting with vegetarian breakfast casseroles, I landed on this recipe. We now make it every year alongside the usual casseroles and I am so excited to share it with you.

Recipe features

• 8 servings of fluffy egg, hash browns, cheese, and veggie sausage
• Can be doubled, frozen and prepped in advance
• Perfect for family breakfasts, meal prep and holiday meals
• Easy to customize: choose your favorite veggies, shredded cheese and veggie sausage

Since first making this recipe, I've also shared a sweet potato collard green egg bake, egg bites, and mushroom goat cheese frittata that you'll love if you like breakfast casseroles.

Main ingredients

There are five main components to this casserole:

• Hashbrowns: Thawed frozen hashbrowns are used in this recipe. For extra texture and flavor, I like to brown them slightly before adding them to the casserole dish.
• Vegetarian sausage: Such as Morningstar brand. This step isn't necessary, but it helps make this meatless casserole a little "meatier". And it makes the meat-eaters in my family a little happier.
• Bell peppers and mushrooms: I like to use baby bella mushrooms and red bell pepper, but any variety of bell pepper works here.
• Shredded cheddar: Sharp cheddar is the traditional choice, but mozzarella or Italian blend are also good options.
• Eggs mixed with milk. I use large eggs and usually use soy or 2% milk, but any kind of unsweetened, unflavored milk works here.

Step by step recipe instructions

Prepping the ingredients

Sauté the veggies until softened instead of adding them straight to the unbaked casserole. This deepens their flavor and helps prevent the casserole from becoming watery.

If you're short on time you can skip this step and add raw vegetables directly to the other ingredients.

Meanwhile, cook the hashbrowns for 5-6 minutes in a separate pan until lightly golden and thawed.

You can skip this step but you do need to let the hashbrowns thaw completely before adding them to the casserole dish.

Assembling the casserole

1. Lightly oil an 8x11 or similarly sized baking dish. Add the defrosted or lightly brown hash browns and spread into an even layer.
2. Add the crumbled veggie sausages and veggies.
3. Sprinkle the cheese across the veggies and sausage.
4. Pour on the whisked eggs, making sure to evenly cover all parts of the casserole so that there are no dry spots.
5. Bake in the oven on the middle rack and for 35-40 minutes. It's ready when the edges are golden and beginning to pull away from the dish. A toothpick inserted in the center should be completely clean but still moist. Let rest for 5 minutes before slicing.

Recipe FAQ

Make ahead and storage tips

• Make ahead: This breakfast casserole can be prepared up to 24 hours in advance. Assemble the entire casserole according to the recipe instructions. Cover with foil or other lid and refrigerate. When ready to bake the casserole, remove the lid and bake in the oven for 35-40 minutes at 350.
• Leftovers: For best quality, cover egg casserole and keep refrigerated for 3-4 days.
• How to reheat: Reheat individual slices in the microwave in about a minute. To reheat the entire casserole, cover with a lid or foil and reheat at 350F until warmed through.
• Freezing: This recipe freezes well. I recommend freezing the casserole already sliced or as individual pieces. Reheat individual servings in the microwave in just 1-2 minutes.

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📖 Recipe

Print Recipe

4.67 from 6 votes

Easy Vegetarian Breakfast Casserole

An easy casserole that uses eggs, hashbrowns, cheese, veggie sausage, mushrooms & bell peppers. Can be made ahead. 

Prep Time10 minutes mins

Cook Time35 minutes mins

Total Time45 minutes mins

Servings: 8 servings (slices)

Author: Cassidy Reeser, MS, RD

Ingredients

• ▢ 5 ounces veggie sausages see note #2
• ▢ 8 ounces frozen hash browns thawed, see note #1
• ▢ 1 tablespoon olive oil any neutral oil works
• ▢ ½ cup diced bell peppers
• ▢ 4 ounces cremini mushrooms diced
• ▢ 8 large eggs
• ▢ ½ cup milk of choice
• ▢ ½ teaspoon salt
• ▢ ¼ teaspoon garlic powder
• ▢ ¼ teaspoon onion powder
• ▢ ¼ teaspoon black pepper
• ▢ 1 cup shredded sharp cheddar cheese

Instructions

• Preheat oven to 350 degrees F. Lightly oil an 8x11, 8x8 or similarly sized baking dish.
• Optional: Cook the hash browns in a skillet for 5-6 minutes, until lightly golden. They don't need to be cooked all the way through but should be thawed.
• Cook veggie sausages according to package instructions. Use a knife or spatula to crumble up into bite-sized pieces.
• Heat a large skillet over medium-high heat. Once hot, drizzle in olive oil. Add the bell peppers and mushrooms, sautéing until softened, about 5-6 minutes.
• In a large mixing bowl, use a whisk to mix together the eggs, milk, salt, garlic powder, onion powder and black pepper as if you were making scrambled eggs. Set aside.
• Assemble the casserole: Layer the hash browns in the lightly oiled casserole dish. Add the crumbled sausage and sautéed peppers and mushrooms. Sprinkle on 1 cup of cheddar cheese. Pour the eggs over the cheese, making sure to cover all dry areas.
• Bake uncovered for 35-40 minutes, or until golden brown and the eggs are cooked through at the center. The edges should be turning golden and pulling away from the pan.
• Let rest 5 minutes before slicing and serving. Enjoy!

Video

Notes

1. Hash browns need to be thawed before adding to the casserole. I usually cook them in a cast iron skillet for a few minutes to lightly brown them and add flavor, but this is optional.
2. Veggie sausage: I use Morningstar maple-flavored breakfast sausages or Lightlife links. You can also replace vegetarian sausage with equal amounts of sautéed mushrooms.
3. To make ahead: Vegetarian egg casserole can be prepared up to 24 hours in advance. To make ahead, assemble the casserole according to the recipe instructions. Cover with foil or other lid and refrigerate (I love these baking dishes because they come with reusable lids). When ready to make, remove the lid and bake in the oven for 35-40 minutes at 350F.
4. Leftovers and reheating: Egg casserole will last in the fridge for 3-5 days and can be reheated in the microwave in about a minute.
5. Freezing: Freeze individual portions wrapped in foil or freeze-safe containers for up to 3 months. Reheat individual pieces in the microwave in 1-2 minutes.

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Serving: 1sliceCalories: 216kcalCarbohydrates: 11gProtein: 15gFat: 11gSaturated Fat: 4gCholesterol: 180mgSodium: 509mgPotassium: 331mgFiber: 2gSugar: 1gVitamin A: 730IUVitamin C: 17mgCalcium: 198mgIron: 2.1mg

Author's note: This recipe was originally shared November 2018. It was updated September 2021 with new photos, a video and more tips. The recipe remains the same.