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 vegetarian breakfast casserole every single year for Christmas morning but it's a great breakfast option all year round.
When I became a vegetarian almost a decade ago, I knew that I had to find an alternative to my family's annual sausage egg breakfast casserole.
After a few years of experimenting with vegetarian breakfast casseroles, I landed on this recipe, which uses vegetarian sausage, hashbrowns, eggs, and vegetables. We now make this recipe every year!
Why this recipe works
- Balanced and hearty: My breakfast casserole makes 8 slices of fluffy egg, hash browns, cheese, and veggie sausage.
- Family favorite: I've been making this recipe for Christmas morning breakfast for more than 8 years and it's based on an egg casserole recipe that my mom has been using for over 20 years. This vegetarian breakfast casserole is tried and true!
- Versatile: This recipe can be doubled, frozen, and even prepped in advance or turned into an overnight breakfast casserole.
- Easy to customize: Choose your favorite vegetables, shredded cheese, and veggie sausage to make this recipe your own.
There are five main components to my vegetarian breakfast 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 or Beyond brands. 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 2% milk or soy 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 egg casserole from becoming watery.
Time-saving tip: 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.
Time-saving tip: 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
- Lightly oil an 8x11-inch or similarly sized baking dish. Add the lightly browned hash browns and spread into an even layer.
- Add the crumbled veggie sausages and veggies. Spread into an even layer.
- Sprinkle the cheese across the veggies and sausage.
- Pour on the whisked eggs, making sure to evenly cover all parts of the casserole so that there are no dry spots.
- Bake the egg casserole on the middle oven rack 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.
This recipe works best in an 8x8, 8x11-inch or similarly sized baking dish. I alternate between glass and ceramic dishes. If doubling the recipe, I recommend using a 9x13 dish. You may need to bake it for up to 50 minutes if doubling the recipe.
Yes, you can easily casserole this breakfast casserole dairy-free by using non-dairy milk in place of milk and your favorite vegan shredded cheese. Make sure to use unsweetened, unflavored milk.
Feel free to mix in whichever veggies you like. Zucchini, onions, spinach, and broccoli are all great options.
No. One of the reasons that I like this recipe is because it can be prepped ahead and refrigerated overnight, but it can also be assembled and baked in the same morning.
There are a few ways to tell when the casserole is fully cooked. The most foolproof option is to check that the temperature is 160F by using a thermometer. For visual cues, note that the edges should be golden and pulling away from the casserole dish. Also, the casserole will be gently puffed up. Insert a knife in the center of the eggs. It should come out clean and not wet.
Make ahead instructions
This breakfast casserole can be prepared up to 24 hours in advance and refrigerated until ready to bake.
Assemble the 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 350F.
- Storage: For best quality, cover the 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 for just 1-2 minutes.
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Vegetarian Breakfast Casserole
- 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
- 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!
- 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.
- Veggie sausage: I use Morningstar maple-flavored breakfast sausages or Lightlife links. You can also replace vegetarian sausage with equal amounts of sautéed mushrooms.
- 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.
- 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.
- 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.