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Make-Ahead Breakfast Casserole

A delicious, make-ahead breakfast casserole that combines layers of cubed bread, savory egg custard, cooked sausage, and fresh vegetables, perfect for holiday brunches or weekend gatherings.
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Prep Time 20 minutes
Cook Time 45 minutes
Total Time 1 hour 15 minutes
Servings: 10 servings
Course: Breakfast, Brunch
Cuisine: American
Calories: 250
Ingredients Method Notes

Ingredients
  

Casserole Base
  • 6 cups cubed bread (sourdough or French bread, day-old preferred) Day-old bread works best to avoid mushiness.
  • 1 tablespoon olive oil For greasing the baking dish and cooking sausage.
Meat and Vegetables
  • 1 pound ground pork sausage Bulk sausage recommended, turkey or plant-based alternatives can be used.
  • 1/2 medium yellow onion, diced
  • 3 cloves garlic, minced
  • 1 cup chopped bell peppers (any color)
  • 1 cup sliced mushrooms
  • 2 cups fresh spinach
  • 1 teaspoon dried rosemary or Italian seasoning
Egg Custard
  • 8 large eggs
  • 1 cup milk or half-and-half Half-and-half will produce a richer custard.
  • 1 teaspoon salt
  • 1/2 teaspoon freshly ground black pepper
Topping
  • 2 cups shredded cheddar cheese
  • Fresh green onions or parsley, for garnish (optional)

Method
 

Preparation
  1. Grease a 9×13-inch baking dish generously with olive oil or non-stick cooking spray.
  2. Spread the cubed bread evenly across the bottom of the greased dish.
Cooking the Sausage
  1. Heat olive oil in a large skillet over medium heat.
  2. Add the ground pork sausage and cook until browned, about 5 to 7 minutes.
Sautéing the Vegetables
  1. Add diced onion and minced garlic to the pan and cook for 2-3 minutes until the onion is soft.
  2. Add chopped bell peppers and sliced mushrooms, cooking for another 3-4 minutes.
  3. Stir in fresh spinach and cook until wilted, about 1 minute.
Layering the Casserole
  1. Spoon the sausage and vegetable mixture evenly over the bread cubes.
Preparing the Custard
  1. In a bowl, whisk together eggs, milk or half-and-half, salt, and black pepper.
  2. Pour the egg mixture evenly over the casserole.
Chilling
  1. Scatter shredded cheddar cheese on top, cover tightly, and refrigerate for at least 30 minutes, preferably overnight.
Baking
  1. Remove from fridge, let sit at room temperature for 10-15 minutes, then preheat oven to 375 degrees F.
  2. Bake uncovered for 40-45 minutes until the top is golden brown.
Serving
  1. Let the casserole rest for 10 minutes before cutting into squares and serving.

Notes

This casserole can be customized with different proteins, vegetables, or cheeses. Leftovers store well in the fridge for up to 5 days. It can also be frozen after baking for up to 2 months.