Cheesy Vegetarian Breakfast Casserole is a perfect recipe to make whenever you have vegetables that need to be used! We used mushrooms, green peppers, Feta, and Monterey Jack for the vegetarian breakfast casserole, but see other options for vegetables and cheese in the post.

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Cheesy Vegetarian Breakfast Casserole shown in baking dish.

This Cheesy Vegetarian Breakfast Casserole is something I first made years ago, and this combination is still one of my favorites for a meatless breakfast casserole. For the version you see in the photos I used mushrooms and green peppers, but see suggestions below for lots more tasty ideas for a vegetarian breakfast casserole. And there are lots of options for cheese to use in a recipe like this as well, but personally I would always include Feta cheese!

Breakfast casseroles are always a great way to use leftover vegetables, and I think recipes like this are so perfect to make on the weekend and have a tasty breakfast to reheat during the week! And whether you’re a vegetarian or just someone who likes vegetables, I hope you enjoy trying this.

What ingredients do you need for this recipe?

(This is only a list of ingredients; please scroll down for complete printable recipe. Or if you use the JUMP TO RECIPE link at the top of the page, it will take you directly to the complete recipe.)

  • mushrooms
  • green bell pepper
  • Olive Oil (affiliate link)
  • crumbled Feta cheese
  • grated Monterey Jack cheese
  • Spike Seasoning (affiliate link), or other all-purpose seasoning blend
  • fresh ground black pepper to taste
  • eggs
  • green onions (optional)

What other vegetables work in Cheesy Vegetarian Breakfast Casserole?

I love the combination of mushrooms and green bell pepper in this recipe. But here are more options; all the veggies need to be slightly pre-cooked as shown in recipe instructions:

  • Switch out the green pepper for red bell pepper.
  • Switch out the green pepper for asparagus, cut small.
  • Switch out the green pepper for about 2 cups chopped kale, Swiss Chard, or spinach.
  • Switch out the green pepper for broccoli, chopped small.
  • Switch out the green pepper for one medium zucchini, chopped small.
  • Switch out the mushrooms for diced cherry tomatoes (drained).
  • Switch out the mushrooms for artichoke hearts.

What other cheeses work in Cheesy Vegetarian Breakfast Casserole?

It’s probably obvious that I LOVE Feta Cheese, but if you’re not a fan here are some other cheeses you can use. Be sure to choose two cheese varieties that go together well.

  • grated Mozzarella cheese
  • grated cheddar cheese
  • grated Swiss cheese
  • crumbled goat cheese
  • crumbled Cotija or Queso Fresca cheese
  • rinsed and drained cottage cheese
  • grated Parmesan, Romano, or Asiago cheese

Tips for making breakfast casseroles:

Before you make this recipe you may want to read my Low-Carb Breakfast Casserole Master Recipe which has instructions for different sizes of pans and ingredient options as well as 15+ of my favorite low-carb breakfast casserole recipes.

Why do I love breakfast casseroles?

It’s been years since I started my personal journey of carb-conscious eating, and if I had to pick one thing that’s helped me, it would be low-carb recipes that can be made on the weekend and then reheated during the week. That’s why I created the Weekend Food Prep category on this site, and breakfast casseroles would top my list of things to make every weekend.

How low in carbs is this vegetarian breakfast casserole?

This flavorful breakfast casserole with vegetables and cheese only has about 4 net carbs per serving.

Want more Keto Breakfast Casseroles?

Check out 25 Family-Friendly Keto Breakfast Casseroles for so many more tasty ideas.

Cheesy Vegetarian Breakfast Casserole collage showing recipe steps.

Steps for making Cheesy Vegetarian Breakfast Casserole:

(This is only a summary of the steps for the recipe; please scroll down for complete printable recipe. Or if you use the JUMP TO RECIPE link at the top of the page, it will take you directly to the complete recipe.)

  1. Preheat oven to 375F/190C and spray casserole dish with non-stick spray or olive oil.
  2. Heat olive oil in frying pan over medium-high heat. Cook sliced mushrooms until they’re slightly browned and liquid has evaporated; then add them to casserole dish.
  3. Add a little more olive oil to pan if needed. Cook chopped bell peppers until they’re starting to soften, about 3-5 minutes. Layer green pepper over mushrooms in the casserole dish.
  4. Crumble Feta cheese and half the Monterey Jack cheese over the vegetables.
  5. Then beat eggs with Spike Seasoning (affiliate link) and black pepper and pour over the vegetable-cheese mixture.
  6. I give it a little stir with a fork, then sprinkle over the rest of the Monterey Jack cheese.
  7. Bake for 25-30 minutes, or until the eggs are set and the top is starting to lightly brown.
  8. Serve hot, sprinkled with green onions if using.
  9. I love breakfast casseroles like this with a little sour cream on top.

Square image for Cheesy Vegetarian Breakfast Casserole shown in baking dish on napkin and cutting board.

More Tasty Vegetarian Breakfasts:

Weekend Food Prep:

This vegetarian breakfast casserole recipe has been added to a category called Weekend Food Prep where you’ll find recipes you can prep or cook on the weekend and eat during the week!

Cheesy Vegetarian Breakfast Casserole shown in baking dish.
Yield: 8 servings

Cheesy Vegetarian Breakfast Casserole

Prep Time 20 minutes
Cook Time 40 minutes
Total Time 1 hour

Make this Cheesy Vegetarian Breakfast Casserole on the weekend and eat it all week! And this can be made with a wide variety of vegetables, depending on what's in the fridge.

Ingredients

  • 8 oz. sliced mushrooms
  • 1 large green bell pepper, chopped
  • 1 T olive oil (or slightly more)
  • 1 cup crumbled feta cheese (or more, to taste)
  • 1 cup grated Monterey Jack cheese (or more, to taste)
  • 2 tsp. Spike Seasoning (see notes)
  • fresh ground black pepper to taste
  • 12 eggs
  • 3 green onions, sliced (optional)

Instructions

  1. Preheat oven to 375F/190C. Spray 8" by 12" glass or crockery casserole dish with olive oil or non-stick spray. (Any dish that’s close to this size will work.)
  2. Wash mushrooms if needed and cut into thick slices.
  3. Cut out stem part of the green pepper, remove seeds, and chop the pepper into pieces about 1/2 to 3/4 inch square.
  4. Heat non-stick frying pan to medium high, add small amount of olive oil, and cook mushrooms 4-5 minutes, until softened and starting to brown. (Be sure they are not still wet.)
  5. Spread mushrooms in bottom of casserole dish.
  6. Add a bit more olive oil to frying pan if needed, and cook chopped green peppers until softened and partly cooked.
  7. Layer peppers over mushrooms in casserole dish.
  8. Crumble feta cheese and half the Monterey Jack Cheese over top of mushroom-pepper mixture. Sprinkle with sliced green onions if using.
  9. Beat the eggs with Spike Seasoning (affiliate link) and black pepper. until yolks and whites are well-combined. (Don’t add salt because Feta cheese is salty enough.)
  10. Pour eggs over mushrooms, peppers, and cheeses. Use a fork to gently stir the mixture so veggies and cheese are well-distributed in the eggs.
  11. Sprinkle the top with the rest of the grated Monterey Jack cheese.
  12. Bake 25-30 minutes, or until casserole is firmly set and top is slightly browned. Sprinkle with sliced green onions if using.
  13. Serve hot. I like to eat this with a dollop of sour cream on top.

Notes

Spike Seasoning (affiliate link) is optional, but highly recommended; use another all-purpose seasoning if you don't have Spike.

Breakfast casseroles like this can be stored in the fridge for at least a week and reheat very well in the microwave or in a pan on top of the stove. If you’re heating in a microwave, be careful not to heat too long or the eggs will get rubbery.

Recipe created by Kalyn.

Nutrition Information

Yield

8

Serving Size

1

Amount Per Serving Calories 244Total Fat 18gSaturated Fat 8gTrans Fat 0gUnsaturated Fat 8gCholesterol 309mgSodium 752mgCarbohydrates 5gFiber 1gSugar 2gProtein 17g

Nutrition information is automatically calculated by the Recipe Plug-In I am using. I am not a nutritionist and cannot guarantee 100% accuracy, since many variables affect those calculations.

Did you make this recipe?

Did you make this recipe? Please leave a star rating (under the PRINT button in the recipe) or share a photo of your results on Instagram! THANKS!


Cheesy Vegetarian Breakfast Casserole shown in baking dish, vertical image.

Low-Carb Diet / Low-Glycemic Diet / South Beach Diet Suggestions:
This Cheesy Vegetarian Breakfast Casserole is a perfect breakfast for low-carb or Keto diets, or for any phase of the original South Beach Diet. South Beach would recommend reduced fat cheese.

Find More Recipes Like This One:
Use Breakfast Recipes to find more recipes like this one. Use the Diet Type Index to find recipes suitable for a specific eating plan. You might also like to follow Kalyn’s Kitchen on Pinterest, on Facebook, on Instagram, on TikTok, or on YouTube to see all the good recipes I’m sharing there.

Historical Notes for this Recipe:
This vegetarian breakfast casserole with lots of cheese was first posted in 2007! The recipe was updated with better photos in 2014 and updated again with new photos and more information in 2024.

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