Now entering winter weekend hibernation mode! This Vegetarian Breakfast Casserole is just the sort of recipe to enjoy in PJ-clad style. It’s sized for a crowd, can be prepped well in advance (overnight if you like!), and is easily adaptable to a variety of diets.

A pan with a vegetarian breakfast casserole sliced for a crowd with a slice of the casserole on a plate

Whether you are hosting a hoard of out-of-town guests, need a crowd-pleasing recipe for a special brunch, or simply want a lazy-day sort of breakfast that you can eat slices of in your sweatpants at your leisure, savory egg bakes like this one are spot-on for the season.

I consider myself a bit of a breakfast casserole connoisseur, a distinction I owe to my mother.

Every year at the holidays, her three adult children—plus our spouses and my nieces—all squeeze back under her roof. Each morning, my Mom has a crowd-sized breakfast planned for her hungry crew, and while the sides might change, a breakfast casserole is always on the menu.

As a collective, we prefer a savory breakfast casserole like this one over a sweet one (all the more room for a side of Puff Pastry Cinnamon Rolls). They’re almost always egg based, with lots of delicious mix-ins.

Every year around this time, I’m eager to go home and share a big breakfast with my family, and that enthusiasm bubbles over into my cooking. Over the years, I’ve shared a lineup of breakfast casseroles like Crockpot Egg Casserole, Everything Bagel Breakfast Casserole, and for the sweet fans, the ultimate Overnight French Toast.

I hope you’re eager for a big breakfast too. This casserole is fully loaded with roasted vegetables and although it’s vegetarian, it is plenty hearty and satisfying— fit for a breakfast feast!

Don’t let the word “breakfast” in this recipe’s title fool you either; this vegetarian casserole isn’t limited only to the AM hours. I loved eating it reheated for fast, healthy lunches and dinners.

Plus, since this time of year tends to turn PJs into an all-day wardrobe, this recipe is in ideal alignment with that laidback sentiment.

In addition to being vegetarian, this casserole is naturally low carb and gluten free. We love ours with a shower of feta on top, but it can easily be omitted if you’d like the casserole to be dairy free.

Whether you’re cooking for a group with varied dietary needs or you just love a hearty, delicious breakfast that has the added benefit of being good for you, this casserole checks the boxes.

Low carb vegetarian breakfast casserole in a baking dish packed with vegetables

How to Make a Delicious Vegetarian Breakfast Casserole

Below, you’ll find my favorite mix of vegetables for this breakfast casserole recipe, but it is by no means the only tasty combination. Feel free to swap these out for others, depending upon what you and your family prefer.

The Ingredients

  • Sweet Potatoes. They’re deliciously surprising! You’ll love how tender and creamy they taste, and they make the casserole especially filling. If you’ve never added roasted sweet potatoes to an egg bake before, now is the time.
  • Mushrooms. Mushrooms add a touch of earthy flavor to this casserole. Be careful not to use sliced mushrooms or they may overcook.
  • Broccoli. My green, nutrient-packed addition to this vegetarian casserole.
  • Red Bell Pepper + Onion. I love the pop of color that red bell peppers add. Once roasted, both of these veggies bring just the right amount of sweetness to the dish.
  • Eggs. Our key ingredient for bringing this casserole together. The eggs will take on all the other scrumptious flavors in the dish.
  • Milk. The milk helps the egg mixture become extra creamy.
    • You can use a non-dairy milk, if you need this recipe to be dairy free.
  • Italian seasoning. A powerhouse of seasoning that’s perfect for complementing roasted veggies.
  • Ricotta Cheese. A light, fluffy, and dangerously tasty cheese. The slightest hint of sweetness makes it an excellent pairing for the roasted veggies.
  • Fresh Herbs. Basil, thyme or parsley would work best here.

The Directions

  1. Lightly coat 2 large baking sheets and a 9×13-inch casserole dish with nonstick spray.
  2. Place the vegetables in a bowl and drizzle with the oil. Sprinkle with salt and pepper, and toss. Evenly distribute the vegetables onto the baking sheets.

    A sheet pan with roasted sweet potatoes, mushrooms, onions, red peppers, and broccoli

  3. Roast the vegetables for 20 minutes at 400 degrees F, until tender. Place half of the roasted vegetables in the casserole dish.

    A delicious and healthy vegetarian breakfast casserole for a crowd

  4. Beat the eggs together with the milk, garlic, and Italian seasoning. Pour the mixture into the casserole dish, and add remaining vegetables. Top with small spoonfuls of the ricotta. (I typically add about 20 to 24.)
  5. Bake for 35 to 40 minutes at 350 degrees F, until the top is golden. Remove, sprinkle with fresh herbs, and serve warm. ENJOY!

Low carb vegetarian breakfast casserole topped with feta cheese

Recipe Variations

  • Dairy Free. Use a non-dairy milk and omit the cheese (or use a non-dairy cheese option).
  • Gluten Free. No changes needed; this breakfast casserole is gluten free as written.
  • Low Carb. Although I adore the sweet potatoes in this recipe, they are higher carb than other vegetables; you can swap the sweet potatoes for a different, lower carb option. Roasted cauliflower would be delicious.
  • Potato Egg and Cheese. Swap the sweet potato for the same amount of diced Yukon gold potatoes. Sprinkle ½ to 1 full cup of shredded cheese such as cheddar or mozzarella over the first layer of roasted vegetables.
  • Add Meat. Now, I truly don’t think this recipe needs meat, even if you aren’t vegetarian. That said, if you can’t resist, feel free to swap one of the sweet potatoes for 8 ounces of sautéed chicken or turkey sausage. You can also sprinkle the top of the finished casserole with cooked and crumbled bacon.

A baking dish with an easy and healthy vegetarian breakfast recipe that's great for a crowd

How to Store and Reheat Breakfast Casseroles

  • To Store. Cover leftover casserole or store in an airtight storage container and place in the refrigerator for up to 3 days.
  • To Reheat. Rewarm the casserole in the oven at 350 degrees F until hot. You can also gently reheat the casserole in the microwave until warmed through.
  • To Freeze. Store leftover casserole in an airtight freezer-safe storage container for up to 3 months. Let thaw overnight in the refrigerator before reheating.
  • I like to wrap and freeze individual slices, then thaw them overnight in the refrigerator for quick meals.

Overnight Breakfast Casserole Prep Option +  Make-Ahead Tips

  • To prep this casserole ahead of time, you can roast the vegetables up to 2 days in advance.
  • You can also fully assemble the casserole, cover it, and refrigerate it overnight. Let it come to room temperature while the oven preheats, then bake as directed.

A baking dish with slices of tasty and low carb vegetarian egg casserole

Recommended Tools to Make This Recipe

Whether you serve it for breakfast, brunch, or brinner, I hope this vegetarian breakfast casserole becomes a well-loved part of your tradition too.

If you try the recipe, please leave a comment below and let me know how it goes. I love hearing from you!

A pan with a vegetarian breakfast casserole sliced for a crowd with a slice of the casserole on a plate
5 from 3 votes
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Vegetarian Breakfast Casserole

Yield: 10 servings
Prep Time:
15 mins
Cook Time:
55 mins
Total Time:
1 hr 10 mins
A filling and hearty vegetarian breakfast casserole with roasted vegetables and cheese. Low carb and gluten free. Prep it overnight for easy entertaining!

Ingredients

  • 2 medium sweet potatoes — peeled and diced
  • 8 ounces whole cremini baby bella mushrooms — quartered (do not use sliced mushrooms or they may overcook when roasting)
  • 1 small head broccoli — cut into florets
  • 1 red bell pepper — diced
  • 1 red or yellow onion — cut into ½-inch dice
  • 1 teaspoon kosher salt
  • ½ teaspoon black pepper
  • 3 tablespoons extra virgin olive oil
  • 12 large eggs
  • ½ cup milk
  • 1 garlic clove — minced
  • 1 ½ teaspoons Italian seasoning — or dried herbs of choice
  • 4 ounces part-skim ricotta cheese
  • Chopped fresh basil — thyme, or parsley (optional)

Instructions

  1. Position racks in the upper and lower thirds your oven and preheat the oven to 400 degrees F. Lightly coat 2 large baking sheets with nonstick spray. Lightly mist a 9x13-inch casserole dish with nonstick spray and set aside.
  2. Place the vegetables in a large bowl and drizzle with the olive oil. Sprinkle with salt and pepper, then toss to coat. Divide the vegetables evenly between the two sheets and spread them into a single layer. Roast the vegetables until tender, about 20 minutes, tossing the vegetables on the pan so they cook evenly and switching the pans’ positions on the upper and lower racks once halfway through. Transfer half of the roasted vegetables to the prepared casserole dish and spread into an even layer. Reduce the oven temperature to 350 degrees F.
  3. Meanwhile, in a large mixing bowl, beat the eggs together with the milk, garlic, and Italian seasoning until evenly blended. Gently pour it into the casserole dish. Scatter the remaining vegetables evenly over the top, then dollop the ricotta over the top in small spoonfuls (I like to add about 20 to 24 spoonfuls; you want to each slice to have a few dollops, but have them be large enough so that you can actually taste them).
  4. Bake the casserole for 35 to 40 minutes, until the casserole is golden on top and the center no longer jiggles when you shake the pan. Remove from the oven and sprinkle with fresh herbs. Serve warm.

Recipe Notes

  • TO STORE
  • TO REHEAT
  • TO FREEZE
Course: Breakfast, brunch
Cuisine: American
Keyword: gluten free breakfast casserole, low carb breakfast casserole, potato egg and cheese casserole, vegetarian breakfast, vegetarian egg bake

Nutrition Information

Amount per serving (1 (of 10)) — Calories: 188, Fat: 11g, Saturated Fat: 3g, Cholesterol: 200mg, Potassium: 513mg, Carbohydrates: 13g, Fiber: 3g, Sugar: 4g, Protein: 11g, Vitamin A: 4774%, Vitamin C: 71%, Calcium: 123%, Iron: 2%

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