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A freshly baked wholesome breakfast casserole, steaming hot and ready to serve.

Hearty Wholesome Breakfast Casserole with Spinach and Bell Peppers

This hearty breakfast casserole is packed with whole-wheat bread, lean sausage, bell peppers, and optional spinach, all baked in a cheesy egg mixture. It's a perfect make-ahead dish for a wholesome and satisfying morning meal.
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Prep Time 20 minutes
Cook Time 50 minutes
Total Time 1 hour 10 minutes
Servings 8 servings
Calories 350 kcal

Equipment

  • 9x13-inch baking dish
  • large skillet
  • large bowl

Ingredients
  

Main Ingredients

  • 12 slices whole-wheat bread crusts removed and cubed (day-old bread recommended)
  • 1 lb lean breakfast sausage chicken or turkey sausage for a lighter option
  • 1 cup chopped bell peppers any color
  • 1/2 cup chopped onion
  • 6 large eggs
  • 1 ¾ cups milk dairy or unsweetened almond/soy milk
  • 1 tsp Dijon mustard
  • 1/2 tsp salt
  • 1/4 tsp black pepper
  • 1 cup shredded cheddar cheese
  • 1 cup chopped spinach optional, but recommended for added nutrition

Instructions
 

Preparation

  • Grease a 9x13-inch baking dish and scatter cubed whole-wheat bread evenly across the bottom.
  • In a skillet, cook sausage until no longer pink, then drain excess fat. Add bell peppers and onion, sautéing for 5-7 minutes until softened; add spinach at the end if using.

Assembly and Baking

  • Spread the cooked sausage and vegetable mixture over the bread cubes in the baking dish.
  • Whisk together eggs, milk, Dijon mustard, salt, and pepper in a large bowl until well combined.
  • Pour the egg mixture over the casserole ingredients, ensuring the bread is saturated and pressing it down gently.
  • Cover and refrigerate for at least 30 minutes, or preferably overnight, for best flavor and absorption.
  • Preheat oven to 375°F (190°C), then uncover and bake the casserole for 30 minutes.
  • Sprinkle cheddar cheese over the partially baked casserole, then return to the oven for another 15-20 minutes until melted and set.
  • Let the casserole stand for 5-10 minutes before slicing and serving to allow it to firm up.

Notes

For an extra boost of flavor, consider adding a pinch of red pepper flakes to the sausage and vegetable mixture. This casserole can be assembled the night before and baked in the morning, making it perfect for entertaining or busy mornings. Be sure to press down on the bread cubes to ensure they fully absorb the egg mixture, preventing dry spots.