This Breakfast Casserole is delicious and nutritious packed with veggies and protein. Perfect for feeding a crowd, whether it’s brunch, lunch or easy meal prep for the week.
This Breakfast Casserole has recently saved us...as you guys know, I recently had a baby so I barely have time to cook these days. So when I do, I always make something that can last a few days for meal prep and this casserole has come to the rescue! It's packed with hearty ingredients and a dish you can enjoy anytime of the day - for breakfast, lunch or dinner. Think of it as an oven baked frittata that’s easy to throw together, even my husband can make it which is a plus!
Whilst we've just been enjoying it ourselves, it's also great to feed a crowd so its perfect over holidays such as Christmas or Easter that everyone can share - you could also make it ahead to save time. Instead of adding meats like bacon or sausage that are usually in breakfast casseroles, my recipe is a vegetarian version that's equally if not more tasty. Its also healthy, packed with protein and veggies. You can even throw in any leftover vegetables you have on hand and make it your own every time.
Table of Contents
Recipe Highlights
- Easy: Simple steps and basic ingredients anyone can make
- Healthy & Nutritious: Packed with vegetables, protein, fiber and nutrients
- Versatile: Perfect for brunch, meal prep, or feeding a crowd, using any veggies you have on hand
Ingredients and Substitutions
- Eggs are the base of the liquid mixture, I always opt for organic free range eggs.
- Potatoes (white or brown potatoes) are diced and roasted, adding heartiness and carbs. You can also use chopped frozen hash browns for convenience
- Onion brings depth of flavor. Swap with shallots or omit if preferred
- Mushrooms add earthy richness, especially as there's no meat
- Baby spinach provides freshness and color. Kale or swiss chard work as a great substitute
- Sun-dried tomatoes give a tangy salty flavor
- Grana padana cheese adds creamy salty goodness. However any shredded cheese will work such as cheddar cheese
- Milk of choice - I’ve used soy milk. It helps create a smooth liquid base. Dairy or other plant-based options are fine as long as they're unsweetened
- Extra virgin olive oil sautés the veggies. Swap for butter or another oil
- Other veggie options - you can use zucchini, bell peppers or fresh cherry tomatoes
How to make Breakfast Casserole
This easy breakfast casserole is one you’ll come back to again and again. Packed with roasted potatoes, sautéed veggies, eggs and melted cheese, its hearty and full of flavor. Follow my simple steps below (note quantities are listed in the recipe card below)
Step 1: Add diced potatoes to a baking dish (12x8 inch / 30x20 cm in size). Toss with olive oil, salt, pepper and rosemary. Roast for 20 mins in preheated oven of 400°F (200°C)
Step 2: Whilst potatoes are roasting, heat olive oil in a pan and sauté onions
Step 3: When the onions are translucent, add mushrooms and sauté
Step 4: Once mushrooms are browned, season, add spinach, and cook until wilted. Remove from heat
Step 5: Lightly whisk eggs in a bowl then add milk, salt and pepper and whisk to combine
Step 6: Remove potatoes from oven then reduce heat to 350°F (180°C)
Step 7: Add the potatoes, sautéed veggies and ¾ of the cheese to the eggs. Mix to combine
Step 8: Grease the same baking dish with olive oil, pour in mixture and smooth the top. Sprinkle remaining cheese and sun-dried tomatoes. Bake for 25–35 minutes
Step 9: Remove from oven and test with a toothpick - it should come out clean
Step 10: Cool for 10–15 minutes in the dish before slicing into 12 pieces and serving. Enjoy!
Tips and Tricks
- Whisk your eggs thoroughly before adding the cooked veggies
- Always save some cheese and sun-dried tomatoes to garnish the top before baking
- Ensure to let the dish cool for 10-15 minutes before slicing to allow the middle to set
- Get creative with the flavors and feel free to swap for veggies you already on hand
Storage Instructions
- Store leftovers in an airtight container in the refrigerator for up to 4 days
- Reheat individual portions in the oven, air fryer or microwave until warmed through. You can even enjoy it cold from the fridge
- Freeze individual slices for up to 1 month, then thaw and reheat
Make Ahead Instructions
To save time or if preparing for a gathering, there are two ways to make this easy breakfast casserole ahead:
- Cook the veggies the day before, then on the day whisk the egg mixture, pour in and bake, OR;
- Prepare the casserole mixture the day before and refrigerate covered, then bake on the day. Ensure to leave the casserole out of the fridge while the oven is preheating to bring it close to room temperature. Note, it may need a little longer cook time so ensure to check with a toothpick or fork
FAQs
A breakfast casserole is a simple baked dish made with eggs, milk and ingredients like potatoes, veggies and cheese. Some versions include meat, but this one is vegetarian and just as satisfying
Breakfast casseroles are usually baked uncovered so the top can become golden. If it browns too quickly, loosely cover it with foil so the center can finish cooking without burning
Yes, it freezes well. Place slices on a tray in a single layer and freeze until firm. Once frozen, transfer to an airtight container or bag with parchment paper between layers to prevent sticking. This way, you can easily grab one piece at a time. Freeze for up to 1 month, then thaw and reheat
More Oven Bake Meals
Looking for other recipes like this? Try these:
I love seeing your creations and remakes, so be sure to rate the recipe, comment and share your photo on Instagram so I can share the love!
Recipe
Breakfast Casserole (Easy, Healthy & Delicious)
Ingredients
- 12 large eggs
- 10oz / 300g mushrooms
- 2 medium potatoes
- 1 medium onion
- 2 cups packed baby spinach
- ⅓ cup sun-dried tomatoes - plus 2 tablespoons for garnish
- 1 cup grated Grana Padano cheese (or cheddar)
- ¾ cup milk of choice - I’ve used soy milk
- 2 ½ tablespoons extra virgin olive oil
- 1 teaspoon dried rosemary or parsley
- Salt and black pepper to taste
Instructions
- Prepare the veggies - finely dice the onion, slice the mushrooms, chop the potatoes into small cubes and chop up the sun-dried tomatoes with scissors. Preheat the oven to 400℉/200℃
- Add the diced potatoes into a baking dish (12x8 inch / 30x20 cm in size). Add 1 ½ tablespoons of olive oil, season well with salt and pepper and the rosemary and toss together. Roast in the oven for 20 minutes until cooked and lightly golden brown
- While the potatoes are roasting, saute the onions in a large skillet with a tablespoon of olive oil. Once translucent add the mushrooms and saute together
- Once mushrooms have browned, season with salt and pepper and add the spinach. Saute until wilted then remove the pan from the heat
- Crack the eggs in a large bowl and lightly whisk. Add the milk, season with salt and pepper and whisk again until combined
- Once potatoes are ready, remove from the oven and reduce oven temperature to 350℉/180℃
- Add the roasted potatoes, sauteed veggies and ¾ of the grated cheese to the eggs and stir to combine
- Brush or spray olive oil to the bottom and sides of the same baking dish and pour in the mixture, flattening the top. Sprinkle the remaining cheese on top along with the remaining sun-dried tomatoes
- Bake for 25-35 minutes - depending on oven strength, the top should be lightly golden brown. Check that its cooked with a toothpick, it should come out clean in the middle and not feel giggly or wet anymore
- Allow it to cool for 10-15 minutes in the dish before slicing into 12 even pieces. Serve it up and enjoy your delicious and nutritious Breakfast Casserole!
Notes
- Garnish - reserve some cheese and sun-dried tomatoes for the top before baking
- Resting - let cool for 10–15 minutes before slicing so the center sets
- Get creative - use any left over veggies on hand or swap in zucchini, bell peppers or cherry tomatoes
- Make-ahead - two ways you can do it - 1) You can either cook the veggies the day before, then on the day prepare egg mixture, pour and bake it - 2) Or prepare the casserole mixture the day before and refrigerate. The next day, let it sit at room temp while the oven preheats, then bake. It may need extra baking time, so remember to test with a toothpick for doneness
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