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Egg and Potato Breakfast Casserole is an easy vegetarian breakfast bake loaded with veggies. It is completely customizable and can be made ahead of time. |

Egg and Potato Breakfast Casserole

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5 from 24 reviews

  • Author: Sam | Ahead of Thyme
  • Total Time: 45 minutes
  • Yield: 6 servings
  • Diet: Vegetarian


Egg and Potato Breakfast Casserole is an easy vegetarian breakfast bake loaded with veggies. It is completely customizable and can be made ahead of time. 


  • 1 tablespoon olive oil
  • 1 small onion, finely chopped
  • 1 medium green bell pepper, diced
  • 2 medium russet potatoes, diced into small 1/2 inch cubes
  • 3/4 teaspoon salt, divided
  • 3/4 teaspoon ground black pepper, divided
  • 5-6 large eggs
  • 1/2 cup cheddar cheese, shredded (optional)


  1. Preheat oven to 350 degrees F. Lightly grease a 9-inch square casserole dish and set aside.
  2. In a large skillet, heat oil over medium heat. Sauté the onions for 1 minute, then add green peppers, potatoes, 1/2 teaspoon salt, and 1/2 teaspoon black pepper and continue to sauté for another 4 minutes until the onions are soft and tender.
  3. Transfer the vegetable mixture to the prepared casserole dish and spread out evenly.
  4. In a medium mixing bowl, beat together the eggs and remaining salt and pepper. Pour the egg mixture evenly over the vegetables in the casserole dish. Sprinkle some cheddar cheese on top (optional).
  5. Bake for 35-40 minutes, or until eggs are cooked firmly.


How to double the recipe: You can easily double the recipe and bake in a 9x13-inch casserole pan instead.

Make ahead instructions: One of my favorite things about this dish is that you can prepare it ahead of time. There is nothing better than waking up in the morning and just popping an egg casserole into the oven. There are 2 ways to prep it in advance:

  • Prep and bake later
  • Combine all your ingredients (leaving out the potatoes) into your casserole dish the night before, cover it with aluminum foil or plastic cling wrap and store in the fridge until you are ready to bake. You can chop the potatoes but store them in a container with water so that they are submerged (to prevent browning). In the morning, drain and add the potatoes to the casserole pan and give it a quick stir. Sprinkle on some cheddar cheese (optional) and allow it to come to room temperature. Then, pop it into the oven.
  • Bake and reheat: Make the breakfast casserole dish and actually bake it the night before. Allow it to cool to room temperature and then store it covered in the fridge. Remember that this is the kind of dish that you want to eat warm so simply pop it into a preheated 350F oven in the morning for about 10 minutes to reheat.

How to store: Store any leftover breakfast egg bake in an airtight container in the fridge for up to 2-3 days.

How to reheat: Reheat in a 350F preheated oven for 10 minutes until warm, or reheat slices in a 350F air fryer for 5-10 minutes or in the microwave until warmed through.

How to freeze: To freeze this breakfast casserole, prepare the recipe as directed and assemble into the casserole dish but don't bake it. Cover it tightly with plastic cling wrap and wrap it again with aluminum foil. Store in the freezer for up to 3 months. Allow it to thaw overnight in the refrigerator, then allow it to come to room temperature before popping into the oven and baking as per the recipe instructions. 

  • Prep Time: 10 minutes
  • Cook Time: 35 minutes
  • Category: Eggs
  • Method: Bake
  • Cuisine: American