This Breakfast Casserole is my favorite savory holiday breakfast! It’s hearty and so delicious, filled with sausage, vegetables and cheese. See the notes below for make ahead instructions – a convenient option for holiday mornings!

Looking for more holiday breakfast ideas? Try my French Toast Casserole, Broccoli Quiche and Cinnamon Rolls next!

Sliced breakfast casserole in baking dish.

The best Breakfast Casserole I’ve ever made

If you’re looking for a savory breakfast to make this holiday season, I can’t think of a better option than this breakfast casserole. I love this recipe because it’s loaded with flavor-packed ingredients, like breakfast sausage, cheese, green onions and veggies. It’s hearty, filling and great for feeding a crowd or meal prepping breakfast for the week.

This recipe is also easily adaptable – I’ve made it with bacon instead of sausage, and you can swap out the veggies for your favorites. I must say, though, that I’m really partial to the combination of ingredients I’ve used in this recipe – it’s absolutely delicious!

Slice of casserole on a spatula held over the baking dish.

On holiday mornings I like to relax and spend time with my family, not be stuck in the kitchen. Which is why I love that this breakfast casserole can be prepped the day before, refrigerated overnight, and then baked in the morning. I usually keep things simple and serve it with a side of fresh fruit. If you’re including this egg casserole in a brunch spread, it’s great with Homemade Biscuits or Scones (if you’re looking for something sweet) and a Fruit Salad.

Ingredients You’ll Need

Ingredients for breakfast casserole recipe with labels: bell pepper, mushrooms, eggs, green onions, onion powder, olive oil, oregano, chili powder, garlic powder, salt, pepper, sweet potato, breakfast sausage, milk and cheese.

How to Make Breakfast Casserole

Here’s an overview of how to make this breakfast casserole. Find the full printable recipe with ingredient amounts below.

Roast sweet potatoes. Cube them, then season with olive oil, chili powder, salt and pepper. Bake at 425° F, until tender in the middle and golden on the edges, tossing once halfway through the cook time.

Cubed seasoned sweet potatoes on parchment paper-lined baking sheet.

Cook sausage and vegetables. In a large skillet, cook the sausage, crumbling, for 2-3 minutes. Then add the chopped mushrooms and diced bell peppers to the skillet and continue cooking until the sausage is browned and cooked through, stirring often.

Cooked sausage, mushrooms and red bell pepper in skillet with a wooden spoon.

Combine eggs with other ingredients. Whisk together the eggs, milk, garlic powder, onion powder, dried oregano, salt and pepper. Stir in the roasted sweet potatoes, cooked sausage, mushrooms and bell peppers, ⅔ of the green onions and ⅔ of the shredded cheese. Pour the egg mixture into a greased baking dish. Sprinkle the rest of the green onions and shredded cheddar over the top.

Cheese and green onions added to egg/milk/seasoning mixture.
Unbaked casserole in baking dish, ready to go in the oven.

Bake at 350° F for 35-45 minutes, until the edges are golden brown and the eggs are set in the center.

Recipe Variations

One of my favorite things about this breakfast casserole is that it’s so easy to adapt to your tastes and to what you have on hand. Here are some suggestions for ways to customize the recipe:

  • Bacon or Ham: Use cooked bacon (I like to cook bacon in the oven) or diced ham instead of sausage. If doing so you’ll only need to sauté the mushrooms and peppers in the skillet.
  • Potatoes: You can substitute Yukon gold potatoes for the sweet potatoes. Chop and roast as directed in the recipe.
  • Vegetarian: Omit the sausage and add an extra 1/4 teaspoon salt to the egg mixture (you lose some salty flavor without the sausage). Or try my Vegetarian Egg Casserole.
  • Vegetables: You can switch up the veggies in this recipe. Try chopped spinach, steamed broccoli or roasted asparagus.
  • Cheese: Try a different cheese, such as sharp white cheddar, mozzarella or pepper jack cheese. 

Make Ahead and Storage Tips

You can assemble, cover and refrigerate the casserole up to 24 hours before baking.  In the morning, let the casserole sit at room temperature while the oven preheats, then bake as directed. This is a convenient option for holiday mornings or when you have guests, and you don’t want to spend extra time in the kitchen.

Leftovers of this casserole reheat well. I recommend reheating individual portions in the microwave. You can also reheat it in a 350° F oven, in a baking dish covered with foil, until hot.

Slice of casserole on a plate with a bite taken out of it.

More Brunch Recipes

Sliced breakfast casserole in baking dish.
5 from 3 ratings

Breakfast Casserole

Servings: 12 servings
Prep Time: 40 minutes
Cook Time: 40 minutes
Total Time: 1 hour 20 minutes
This Breakfast Casserole is my favorite savory holiday breakfast! It's hearty and so delicious, filled with sausage, vegetables and cheese. See the notes below for recipe variations and make ahead instructions – a convenient option for a holiday breakfast!
Print Recipe Leave a Review Pin Recipe

Ingredients

For the Sweet Potatoes:

  • 1 medium/large sweet potato*, peeled (if desired) and chopped into ½-inch cubes (about 3 cups cubed)
  • 1 tablespoon olive oil
  • ½ teaspoon chili powder
  • ¼ teaspoon salt
  • ⅛ teaspoon black pepper

Remaining Casserole Ingredients:

  • 1 pound ground pork breakfast sausage*, (not links)
  • 8 ounces cremini mushrooms, chopped
  • 1 red bell pepper, diced
  • 12 large eggs
  • 1 cup milk, I used whole milk
  • ½ teaspoon garlic powder
  • ½ teaspoon onion powder
  • ½ teaspoon dried oregano
  • ¼ teaspoon salt
  • ¼ teaspoon black pepper
  • 6 green onions, white and light green parts only, chopped, divided
  • 1 cup shredded sharp cheddar cheese, 4 ounces, divided

Instructions
 

  • Roast sweet potatoes: Preheat oven to 425° F. Line a rimmed baking sheet with parchment paper. Place the chopped sweet potatoes in a large mixing bowl. Drizzle with the olive oil and sprinkle on the chili powder, salt and pepper. Toss to coat. Spread the sweet potatoes in an even layer on the baking sheet. Bake for 12 minutes. Then toss/flip and continue baking for 8-10 more minutes, until soft in the center and golden brown on the edges. Wipe out the bowl and reserve for mixing the egg mixture.
  • Reduce oven temperature to 350° F.
  • Meanwhile, brown the sausage and sauté veggies: Heat a large skillet over medium heat. Add the sausage to the skillet and cook, crumbling, for 2-3 minutes. Then add the chopped mushrooms and diced bell peppers to the skillet and continue cooking until the sausage is browned and cooked through, stirring often. Remove pan from the heat. Drain off excess grease.
  • Grease a 9×13-inch baking dish.
  • In the large bowl, whisk together the eggs, milk, garlic powder, onion powder, dried oregano, salt and pepper.
  • Stir in the roasted sweet potatoes, cooked sausage, mushrooms and bell peppers, ⅔ of the green onions and ⅔ of the shredded cheese into the egg mixture. Pour the egg mixture into the greased baking dish. Sprinkle the rest of the green onions and shredded cheddar over the top.
  • Bake at 350° F for 35-45 minutes, until the edges are golden brown and the eggs are set in the center. Let rest for 5 minutes before slicing and serving.

Notes

  • Make ahead: Assemble the casserole, cover it and refrigerate for up to 24 hours, before baking. In the morning, let the casserole sit at room temperature while the oven preheats, then bake as directed above.
Recipe Variations:
  • Sausage: If you want less meat in the casserole, you can halve the amount of breakfast sausage used. As written with 1 pound of sausage, there is a fair amount of meat in the casserole.
  • Bacon or Ham: Use cooked bacon (I like to cook bacon in the oven) or diced ham instead of sausage. If doing so you’ll only need to sauté the mushrooms and peppers in the skillet.
  • Potatoes: You can substitute Yukon gold potatoes for the sweet potatoes. Chop and roast as directed in the recipe.
  • Vegetarian: Omit the sausage and add an extra 1/4 teaspoon salt to the egg mixture (you lose some salty flavor without the sausage). Or try my Vegetarian Egg Casserole.
  • Vegetables: You can switch up the veggies in this recipe. Try chopped spinach, steamed broccoli or roasted asparagus.
  • Cheese: Try a different cheese, such as sharp white cheddar, mozzarella or pepper jack cheese. 
Serving: 1/12 recipe, Calories: 277kcal, Carbohydrates: 10g, Protein: 15g, Fat: 19g, Saturated Fat: 7g, Polyunsaturated Fat: 2g, Monounsaturated Fat: 8g, Cholesterol: 203mg, Sodium: 491mg, Potassium: 432mg, Fiber: 2g, Sugar: 3g, Vitamin A: 5507IU, Vitamin C: 15mg, Calcium: 140mg, Iron: 2mg
Nutrition information is an estimate.
Cuisine: American
Course: Breakfast
Tried this recipe?Mention @kristines_kitchen on Instagram or tag #kristineskitchenblog.

 

This site contains affiliate links. If you make a purchase through these links, I may receive a small commission, at no extra cost to you. Thank you for supporting Kristine's Kitchen!