This Vegetarian Breakfast Casserole is just the sort of recipe we need to be enjoying in PJs, at all times of day. Both—meaning the PJs and this recipe—are appropriate at any hour. It makes enough for leftovers, can be prepped well in advance (overnight if you like!), and is easily adaptable to a variety of diets and ingredients.
Whether you are looking for a breakfast that vegetarians can eat, an easy recipe to enjoy all week long, 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.
I consider myself a bit of a breakfast casserole connoisseur, a distinction I owe to my mother.
Whenever my mom has her three adult children—plus our spouses and my nieces—all squished back under her roof, she begins each morning with a crowd-sized breakfast. While the sides might change, a breakfast casserole is the main event.
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 yummy mix-ins.
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 recipe’s title fool you either; this simple vegetarian breakfast isn’t limited only to the AM hours. I love reheating it for fast, healthy lunches and dinners too.
In addition to being vegetarian, this casserole is naturally low carb and gluten free. We love ours with a shower of feta or ricotta baked on top, but it can easily be omitted if you’d like the casserole to be dairy free.
If you love a hearty, delicious breakfast that has the added benefit of being good for you, this casserole checks ALL the boxes. It’s the ideal blend of wholesome and comforting.
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.
- 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 and satisfying savoriness to this casserole. Be careful not to use sliced mushrooms (buy whole ones and quarter them yourself) or they may overcook.
- Broccoli. A 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. The key ingredient holding casserole together. The eggs will take on all the other scrumptious flavors in the dish and add a heap of protein, making this casserole filling.
- Milk. I typically use skim or 2%; whole milk would be richer and unquestionably delicious. 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 or Feta. Both are excelling pairs for the roasted veggies. This ingredient makes the casserole taste special.
- Fresh Herbs. Basil, thyme or parsley would all work well.
- Lightly coat 2 large baking sheets and a 9×13-inch casserole dish with nonstick spray. Toss the vegetables with olive oil, salt, and pepper Evenly distribute the vegetables onto the baking sheets.
- Roast the vegetables for 20 minutes at 400 degrees F, until tender. Layer half of the roasted vegetables in the casserole dish.
- Beat the eggs together with the milk, garlic, and Italian seasoning. Pour the mixture into the casserole dish, and add remaining vegetables on top. Dollop with small spoonfuls of the ricotta or sprinkle with feta.
Bake for 35 to 40 minutes at 350 degrees F, until the top is golden. Remove, sprinkle with fresh herbs, and serve warm. ENJOY!
Vegetarian Breakfast Casserole 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 in carbs 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. (Or try my Healthy Breakfast Casserole with hash browns.)
- Add Meat. Now, I truly don’t think this casserole 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. A breakfast casserole with ham pieces would also be delicious. You can also sprinkle the top of the finished casserole with cooked and crumbled Baked Bacon.
Make Ahead + Storage Tips
- To Prep Ahead. Roast the vegetables up to 2 days in advance, then add them to the recipe as directed.
- Overnight Breakfast Casserole Prep Option. You can also fully assemble the casserole, cover it unbaked, and refrigerate it overnight. Let it come to room temperature while the oven preheats, then bake as directed.
- 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 breakfast casserole in the oven at 350 degrees F until hot. You can also gently reheat individual slices of 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.
What to Serve with Breakfast Casserole
- Bread. Breakfast casserole with whole wheat toast or Easy Drop Biscuits would be a delicious, hearty meal.
- Hash Browns. Breakfast casserole with hash browns is a combination that the entire family will love. (Might I suggest these Sweet Potato Hash Browns?)
- Fruit. For something healthy and light, try a side of fresh fruit with this breakfast casserole.
More Vegetarian Breakfast Recipes with Eggs
- Egg Muffins
- Whole30 Vegetarian Power Bowls
- Freezer Breakfast Quesadilla
- Scrambled Egg Toast with Roasted Asparagus
- Bagel Egg in a Hole with Smashed Avocado
- Easy Kale Feta Egg Toast
Recommended Tools to Make This Recipe
- 9×13 Inch Baking Dish. A classic 3-quart size baking dish is all you need. This one comes with a lid. This set (with lids) is a bargain.
- Small Whisk. I prefer this size for beating eggs and almost all mixing.
Whether you serve it for breakfast, brunch, or brinner, I hope this vegetarian breakfast casserole becomes a well-loved meal in your home too.
If you try the recipe, please leave a comment below and let me know how it goes. I love hearing from you!
Vegetarian Breakfast Casserole
- 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
- 1/2 teaspoon black pepper
- 3 tablespoons extra virgin olive oil
- 12 large eggs
- 1/2 cup milk
- 1 garlic clove minced
- 1 1/2 teaspoons Italian seasoning or dried herbs of choice
- 4 ounces part-skim ricotta cheese
- Chopped fresh basil thyme, or parsley (optional)
- 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 9×13-inch casserole dish with nonstick spray and set aside.
- 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.
- 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).
- 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.
- 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.
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