This vegetarian breakfast casserole is perfect for weekend mornings, holiday brunches, or weekly meal prep. It features diced veggies, shredded hash browns, and a crispy cheese topping. Make it ahead of time for quick prep.
This Vegetarian Hash Brown Breakfast Casserole is the perfect start to your day! Whether it's brunch, Christmas morning, or time for your weekly meal prep, this recipe is sure to hit the spot. The whole family can enjoy this vegetarian breakfast!
It's essentially a frittata or a crustless quiche, baked in a casserole dish and loaded with fillings. Diced onion, bell pepper, jalapeño, frozen shredded hash browns, cheese—you can add anything you want to this breakfast casserole.
This recipe is naturally vegetarian and gluten-free, though you could add some cooked bacon or breakfast sausage if you want. It can also be made the night before to make your morning easier. Keep reading to learn how to make this hash brown casserole.
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Why You'll Love This Recipe
- Get your protein, fat, carbs, and veggies. All in one delicious bake.
- Make ahead and bake in the morning. Just 15 minutes of prep the night before to save you stress in the morning.
- An impressive brunch dish.
- Easily customizable. Customize the fillings based on your tastes!
- Great for meal prep.
- Everyone can enjoy! This recipe is gluten free and vegetarian. You could also make it dairy-free without the cheese and milk.
- Freezes well for later. See below for storage and freezing instructions. Breakfast casserole slices are great to keep on hand for those mornings when you need a quick bite.
What is Breakfast Casserole?
Breakfast casserole is an American dish that is very similar to an Italian frittata or crustless French quiche. It may also be known as a vegetarian egg casserole. Essentially it is baked eggs with several mix-ins, fillings, and/or toppings eaten in slices for breakfast or brunch. This version is baked in a 9x13" casserole dish which makes it super easy.
Need more brunch ideas? You'll also like my moist blueberry muffins, fruit salad with orange dressing, ricotta egg bites, and blended chia pudding cups.
Ingredients & Substitutions
Here is everything you'll need to make this vegetarian breakfast bake:
- Onion—a white or yellow cooking onion
- Red pepper—or any color
- Jalapeño peppers—omit if you don't want the spice
- Shredded potatoes or thawed shredded frozen hash browns—if you're shredding your own, one large russet potato is enough.
- Large eggs
- Milk—use any type you have, I use 2%
- Salt, black pepper, garlic powder, red pepper flakes
- Hot sauce—optional, I use TABASCO
- Shredded cheddar cheese
Optional Ingredients
- If you wish, you could add some cooked meat to this hash brown veggie casserole, like chopped cooked bacon or crumbled sausage.
- Add any veggies you like—including mushrooms, leeks, spinach, etc. I recommend cooking the water out for a few minutes ahead of assembling the casserole.
- You can use any cheese you like or have on-hand—a smoked havarti is great.
Equipment
This recipe requires a 9x13" oven safe dish. I use a ceramic baking dish. You could also use glass. Metal will conduct more heat and cook the outside faster, but you could use a metal pan or well-greased cast iron skillet in a pinch.
Step-by-Step Instructions
Be sure to read the recipe card below for the full ingredient list and instructions.
(Prep) Preheat the oven to 375ºF and grease a 9x13" casserole dish.
I recommend cooking the veggies for 5-8 minutes to allow excess water to evaporate before assembling the casserole. In a skillet over medium heat, add 1 tablespoon butter or olive oil and sauté the diced onion, red bell peppers, jalapeño pepper, and shredded potato until softened. If you are short on time you can skip this step.
(1) In the greased casserole dish, spread the diced onion, peppers, and hash browns in a layer covering the bottom.
(2) In a large bowl or in a blender, whisk together the eggs, milk, hot sauce, and seasonings.
(3) Pour the egg mixture over the veggies, then give it a little shake so the eggs settle evenly. Top with the shredded sharp cheddar cheese.
(4) Bake at 375ºF for 30-40 minutes. Use a temperature probe to check that the centre has reached 160ºF. Broil for 1-2 minutes to melt the cheese more if desired.
Allow the casserole to cool for 10 minutes before cutting and serving—it will be very hot. Slice into 12 pieces and enjoy topped with parsley, green onions or more hot sauce!
Tip: If you like things spicy, try adding crushed red chili flakes to the filling, plus your favorite hot sauce! Or drizzle hot sauce on the freshly baked casserole.
What to Serve With Breakfast Casserole
Here are some of my favorite ways to enjoy this recipe:
- Bring to brunch! If you have a brunch potluck or want to impress your guests, make them this casserole.
- Prepare on Christmas Eve to bake on Christmas Morning! Prep ahead means more time to enjoy.
- Make for breakfast for the week. Bake the casserole on Sunday, then slice and portion enough in the fridge for a quick breakfast for the next 3 days.
- Stock the freezer. Prepare and bake the casserole, allow to cool completely, then slice and freeze in individual portions. Pull them out and reheat whenever you need! See freezer instructions below.
Make Ahead
Prepare the casserole through the end of step 3 above. Cover the dish with foil and refrigerate overnight. In the morning, preheat the oven, uncover, and bake.
Storage & Freezing
Storage: Allow leftover breakfast casserole to cool, then place slices in an airtight container and refrigerate for up to 3 days. Reheat in the oven at 375ºF for about 10 minutes or in the microwave for 2 minutes.
Freezing: Place cooled slices in an airtight container and freeze for up to 2 months. When ready to eat, remove desired portions and microwave for 3 minutes, or bake in the oven at 375ºF for 10-15 minutes.
Expert Tips
Here are some of my top tips and tricks for a delicious breakfast casserole:
- Customize the fillings to your liking! Make it vegetarian, dairy-free, meat lovers, etc!
- Sauté the veggies before assembling the casserole. This will remove excess moisture.
- Shake the casserole dish to distribute egg mixture evenly.
- If preparing ahead, bake no later than the next morning.
- Check the center of the casserole with a probe thermometer to ensure it reaches 160ºF. Timing may vary based on your oven.
- Best served immediately, or freeze. If you don't eat the whole casserole, store slices in the fridge for a maximum of 3 days. Freeze the rest for up to 2 months. Thaw in the microwave or oven at 375ºF until warm throughout.
Frequently Asked Questions
The breakfast casserole should be done in 30-40 minutes. Using a different size baking dish could alter this time. The best way to check is that the casserole is firm and not jiggly or runny, and that the internal temperature of the centre reaches 160ºF.
You can re-heat portions of chicken pot pie skillet in a baking dish in the oven at 350ºF for 20-30 minutes or in a heat-safe dish in the air fryer at 350ºF for 10 minutes until hot and crispy.
This hashbrown breakfast casserole is the perfect thing to make for brunch! Everyone can enjoy this gluten-free, vegetarian, nut-free egg bake. Make it the night before for easy prep and no mess! It's a great way to clear leftover veggies out of your fridge.
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- Gingerbread Banana Bread
Have you made this hash brown breakfast casserole? I'd very much appreciate it if you leave a 5-star rating ⭐️⭐️⭐️⭐️⭐️ and review below, and tag me on instagram @fromoliviaskitchen!
Recipe
Vegetarian Hash Brown Breakfast Casserole
Ingredients
- 1 medium onion diced
- 1 red pepper diced
- 2 jalapeño peppers diced
- 2 cups shredded russet potato or thawed frozen shredded hash browns
- 10 large eggs
- ⅔ cup milk
- 1 teaspoon salt
- ½ teaspoon black pepper
- ½ teaspoon garlic powder
- ½ teaspoon red pepper flakes
- 1 tablespoon hot sauce optional, I use TABASCO
- 1 ½ cup shredded cheddar cheese
Instructions
- Preheat the oven to 375ºF and grease a 9x13" casserole dish.
- I recommend cooking the veggies for 5-8 minutes to allow excess water to evaporate before assembling the casserole. In a skillet over medium heat, add 1 tablespoon butter or olive oil and sauté the diced onion, red pepper, jalapeño pepper, and shredded potato until softened. If you are short on time you can skip this step.
- In a large bowl or in a blender, whisk together the eggs, milk, hot sauce, and seasonings.
- In the greased casserole dish, spread the diced onion, peppers, and hash browns in a layer covering the bottom. Pour the egg mixture around the dish, then give it a little shake so the eggs settle evenly. Top with the shredded cheese.
- Bake at 375ºF for 30-40 minutes. Use a temperature probe to check that the centre has reached 160ºF. Broil for 1-2 minutes to melt the cheese more if desired.
- Allow the casserole to cool for 10 minutes before cutting and serving—it will be very hot. Slice into 12 pieces and enjoy topped with parsley, green onions or more hot sauce!
Notes
- Customize: Use what you have on hand in this casserole! Add some cooked breakfast sausage, mushrooms, spinach, etc.
- Make ahead: Prepare the casserole through the end of step 4. Cover the dish with foil and refrigerate overnight. In the morning, preheat the oven, uncover, and bake.
- Storage: Allow leftover breakfast casserole to cool, then place slices in an airtight container and refrigerate for up to 3 days. Reheat in the oven at 350ºF for about 10 minutes or in the microwave for 2 minutes.
- Freezing: Place cooled slices in an airtight container and freeze for up to 2 months. When ready to eat, remove desired portions and microwave for 3 minutes, or bake in the oven at 350ºF for 10-15 minutes.
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