Make-Ahead Breakfast Casserole With Eggs, Bread, and Cheese

Quick Recipe Version (TL;DR)

• Yield: 12 servings
• Prep Time: 25 minutes
• Cook Time: 55 minutes
• Total Time: 9 hours 30 minutes, including overnight chilling and resting

Quick Ingredients

• 1 tablespoon unsalted butter, softened, for greasing the pan
• 1 pound day-old crusty bread, cut into 3/4-inch cubes, about 10 cups
• 1 pound breakfast sausage, pork or turkey, casings removed if needed
• 1 medium yellow onion, diced, about 1 cup
• 1 red bell pepper, diced, about 1 cup
• 2 garlic cloves, minced
• 2 cups packed baby spinach, roughly chopped
• 10 large eggs
• 2 cups whole milk
• 1 cup half-and-half
• 1 tablespoon Dijon mustard
• 1 teaspoon Worcestershire sauce
• 1 teaspoon kosher salt
• 1/2 teaspoon black pepper
• 1/2 teaspoon smoked paprika
• 2 cups shredded sharp cheddar cheese, divided
• 1 cup shredded Gruyere or Monterey Jack cheese, divided
• 2 tablespoons chopped fresh parsley, plus more for serving

Do This

• 1. Grease a 9-by-13-inch baking dish with 1 tablespoon softened butter.
• 2. Brown 1 pound sausage in a skillet over medium-high heat for 6 to 8 minutes; transfer to a plate.
• 3. Cook onion and bell pepper in the same skillet for 5 minutes, then add garlic and spinach for 1 to 2 minutes.
• 4. Whisk eggs, milk, half-and-half, Dijon, Worcestershire, salt, pepper, and smoked paprika.
• 5. Layer bread, sausage, vegetables, 1 1/2 cups cheddar, and 3/4 cup Gruyere in the dish; pour custard over top and press gently.
• 6. Cover and refrigerate for at least 8 hours or overnight.
• 7. Bake covered at 350°F for 30 minutes, uncover, add remaining cheese, bake 25 minutes more, then rest 10 minutes before serving.

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Why You’ll Love This Recipe

• Made for mornings: Assemble it the night before, then bake it fresh while the coffee brews.
• Feeds a crowd: A 9-by-13-inch pan gives you 12 hearty servings, perfect for holidays, brunches, and houseguests.
• Comforting and flexible: Custardy bread, savory sausage, tender vegetables, and melty cheese make it satisfying, but you can easily customize the add-ins.
• Reliable texture: Day-old bread soaks up the seasoned egg mixture without turning soggy, giving you a casserole that slices cleanly.

Grocery List

• Produce: 1 medium yellow onion, 1 red bell pepper, 2 garlic cloves, 2 cups baby spinach, fresh parsley
• Dairy: 10 large eggs, 2 cups whole milk, 1 cup half-and-half, 2 cups shredded sharp cheddar cheese, 1 cup shredded Gruyere or Monterey Jack cheese, unsalted butter
• Meat: 1 pound breakfast sausage, pork or turkey
• Bakery: 1 pound day-old crusty bread, such as sourdough, French bread, or Italian bread
• Pantry: Dijon mustard, Worcestershire sauce, kosher salt, black pepper, smoked paprika

Full Ingredients

For the Casserole Base

• 1 tablespoon unsalted butter, softened, for greasing the baking dish
• 1 pound day-old crusty bread, such as sourdough, French bread, or Italian bread, cut into 3/4-inch cubes, about 10 cups
• 1 pound breakfast sausage, pork or turkey, casings removed if using links
• 1 medium yellow onion, diced, about 1 cup
• 1 red bell pepper, diced, about 1 cup
• 2 garlic cloves, minced
• 2 cups packed baby spinach, roughly chopped

For the Egg Custard

• 10 large eggs
• 2 cups whole milk
• 1 cup half-and-half
• 1 tablespoon Dijon mustard
• 1 teaspoon Worcestershire sauce
• 1 teaspoon kosher salt
• 1/2 teaspoon freshly ground black pepper
• 1/2 teaspoon smoked paprika

For the Cheese and Finish

• 2 cups shredded sharp cheddar cheese, divided
• 1 cup shredded Gruyere or Monterey Jack cheese, divided
• 2 tablespoons chopped fresh parsley, plus more for serving

Step-by-Step Instructions

Step 1: Prepare the baking dish and bread

Grease a 9-by-13-inch baking dish with 1 tablespoon softened unsalted butter, making sure to coat the corners and sides well. Add the cubed day-old bread to the dish and spread it into an even layer.

If your bread is fresh or very soft, dry it first for the best texture. Spread the cubes on a rimmed baking sheet and bake at 300°F for 12 minutes, stirring once halfway through. The bread should feel dry on the outside but not deeply toasted. Let it cool for 5 minutes before adding it to the baking dish.

Step 2: Brown the sausage

Place a large skillet over medium-high heat. Add the breakfast sausage and cook for 6 to 8 minutes, breaking it into small crumbles with a wooden spoon, until browned and cooked through. Transfer the sausage to a paper towel-lined plate, leaving about 1 tablespoon of drippings in the skillet.

If your sausage is very lean and the pan looks dry, add 1 teaspoon of neutral oil before cooking the vegetables. If there is more than 1 tablespoon of fat in the skillet, carefully spoon off the excess.

Step 3: Cook the vegetables

Reduce the heat to medium. Add the diced onion and red bell pepper to the same skillet and cook for 5 minutes, stirring often, until softened and lightly golden at the edges. Add the minced garlic and cook for 30 seconds, just until fragrant.

Add the chopped baby spinach and cook for 1 to 2 minutes, stirring, until wilted. Remove the skillet from the heat. This quick saute drives off extra moisture, which helps keep the casserole rich and custardy rather than watery.

Step 4: Whisk the seasoned egg custard

In a large mixing bowl, whisk together 10 large eggs, 2 cups whole milk, 1 cup half-and-half, 1 tablespoon Dijon mustard, 1 teaspoon Worcestershire sauce, 1 teaspoon kosher salt, 1/2 teaspoon black pepper, and 1/2 teaspoon smoked paprika. Whisk until the yolks and whites are fully blended and the mixture looks smooth and evenly seasoned.

Stir in 2 tablespoons chopped fresh parsley. The custard should taste savory and balanced; the salt level is designed to account for the bread, eggs, vegetables, sausage, and cheese.

Step 5: Assemble the casserole

Scatter the browned sausage evenly over the bread cubes in the prepared baking dish. Spoon the cooked onion, bell pepper, garlic, and spinach mixture over the sausage. Sprinkle on 1 1/2 cups of the shredded sharp cheddar and 3/4 cup of the shredded Gruyere or Monterey Jack.

Pour the egg custard slowly and evenly over the entire dish. Use the back of a spoon or clean hands to gently press the bread down so every cube begins soaking up the custard. Some bread may still peek above the liquid, which is fine; those pieces will become beautifully golden on top.

Step 6: Chill until the bread soaks up the custard

Cover the baking dish tightly with foil or a fitted lid and refrigerate for at least 8 hours, or up to 24 hours. Overnight chilling gives the bread time to absorb the seasoned egg mixture, creating a tender, cohesive casserole that slices neatly.

If you are short on time, you can let the assembled casserole stand at room temperature for 45 minutes, then refrigerate for 1 hour before baking. The texture will still be good, but the overnight version is the most custardy and evenly set.

Step 7: Bake until puffed, golden, and set

When ready to bake, remove the casserole from the refrigerator and let it sit at room temperature for 30 minutes while the oven preheats to 350°F. Keep it covered with foil for this first part of baking.

Bake the covered casserole at 350°F for 30 minutes. Carefully remove the foil, sprinkle the top with the remaining 1/2 cup sharp cheddar and remaining 1/4 cup Gruyere or Monterey Jack, and bake uncovered for 25 minutes more. The casserole is done when the center is puffed, the top is golden, and an instant-read thermometer inserted into the center reads 160°F.

Step 8: Rest, garnish, and serve

Let the casserole rest for 10 minutes before slicing. This short rest helps the eggs finish setting and makes cleaner squares. Sprinkle with extra chopped parsley, then cut into 12 portions and serve warm.

For a brunch spread, pair it with fresh fruit, a crisp green salad, roasted potatoes, or a simple bowl of berries. It is hearty enough to stand on its own but friendly with almost any breakfast side.

Pro Tips

• Use sturdy bread: Sourdough, French bread, Italian bread, or a rustic country loaf works best. Very soft sandwich bread can become mushy.
• Shred cheese yourself if possible: Freshly shredded cheese melts more smoothly than pre-shredded cheese, which often contains anti-caking starches.
• Do not skip the rest: Ten minutes after baking makes the casserole easier to slice and keeps the custard creamy rather than runny.
• Check the center: The edges will set first, so use an instant-read thermometer in the middle. Aim for 160°F for a fully cooked egg casserole.
• Balance moisture: If adding watery vegetables such as mushrooms, zucchini, or tomatoes, cook them first to remove excess liquid.

Variations

• Vegetarian vegetable casserole: Omit the sausage and add 8 ounces sliced mushrooms plus 1 extra cup diced bell pepper. Saute the mushrooms for 8 to 10 minutes until their liquid evaporates before assembling.
• Ham and Swiss version: Replace the sausage with 2 cups diced cooked ham and use 2 cups Swiss cheese plus 1 cup cheddar. Add 1/4 teaspoon dried thyme to the custard.
• Southwestern style: Use chorizo instead of breakfast sausage, swap the Gruyere for Monterey Jack, and add 1 small can diced green chiles, well drained. Serve with salsa and sliced avocado.

Storage & Make-Ahead

Make-ahead: Assemble the casserole up to 24 hours before baking. Keep it tightly covered in the refrigerator. For the most even bake, let it sit at room temperature for 30 minutes while the oven preheats.

Refrigerating leftovers: Cool leftovers completely, then store in an airtight container in the refrigerator for up to 4 days. Reheat individual portions in the microwave for 60 to 90 seconds, or warm covered in a 325°F oven for 15 to 20 minutes.

Freezing: Freeze baked and cooled portions for up to 2 months. Wrap individual squares tightly, then place them in a freezer-safe bag or container. Thaw overnight in the refrigerator before reheating. For best texture, reheat covered in a 325°F oven until hot in the center.

Nutrition (per serving)

Approximate nutrition per serving, based on 12 servings and made with pork breakfast sausage, whole milk, half-and-half, cheddar, and Gruyere: 425 calories, 24 grams protein, 25 grams carbohydrates, 26 grams fat, 12 grams saturated fat, 2 grams fiber, 5 grams sugar, and 850 milligrams sodium.