This easy breakfast casserole is the perfect make-ahead dish for busy mornings or weekend brunches. Packed with eggs, cheese, sausage, and bread, it’s a comforting, crowd-pleasing meal that can be prepped the night before and baked fresh in the morning. Whether you’re feeding a family, hosting guests, or just want leftovers for the week, this casserole offers convenience and delicious flavor in every bite.
Ingredients
- 1 pound breakfast sausage (pork or turkey)
- 8 large eggs
- 2 cups whole milk
- 1 teaspoon salt
- 1/2 teaspoon black pepper
- 1/2 teaspoon garlic powder
- 1/2 teaspoon onion powder
- 1 teaspoon dried parsley (optional)
- 6 cups cubed day-old bread (about 1 standard loaf, such as French or sourdough)
- 2 cups shredded cheddar cheese (or a blend of cheddar and Monterey Jack)
- 1 cup diced bell peppers (red, green, or a mix)
- 1/2 cup diced onion
- Cooking spray or butter, for greasing the baking dish
Instructions
- Cook the sausage: In a large skillet over medium heat, cook the breakfast sausage, breaking it up with a spatula, until browned and cooked through (about 6-8 minutes). Drain excess fat and set aside to cool slightly.
- Prepare the vegetables: In the same skillet, add the diced onion and bell peppers. Sauté for 3-4 minutes until softened. Remove from heat and let cool.
- Cube the bread: Cut the day-old bread into 1-inch cubes. If your bread is very fresh, you can toast the cubes in a 300°F (150°C) oven for 8-10 minutes to dry them out slightly.
- Mix wet ingredients: In a large bowl, whisk together the eggs, milk, salt, pepper, garlic powder, onion powder, and parsley (if using) until well combined.
- Assemble the casserole: Grease a 9×13-inch baking dish with cooking spray or butter. Spread half of the bread cubes evenly in the dish. Top with half of the sausage, half of the sautéed vegetables, and half of the shredded cheese. Repeat with the remaining bread, sausage, vegetables, and cheese.
- Add the egg mixture: Pour the egg and milk mixture evenly over the layered ingredients. Press down gently with a spatula to help the bread absorb the liquid.
- Cover and refrigerate: Cover the dish tightly with foil or plastic wrap and refrigerate for at least 4 hours, or preferably overnight, to allow the bread to soak up the egg mixture.
- Bake: When ready to bake, preheat your oven to 350°F (175°C). Remove the casserole from the refrigerator and let it sit at room temperature for 20-30 minutes while the oven preheats. Bake, uncovered, for 45-55 minutes, or until the center is set and the top is golden brown. If the top starts to brown too quickly, cover loosely with foil during the last 15 minutes of baking.
- Cool and serve: Let the casserole cool for about 10 minutes before slicing and serving. Enjoy warm!
Tips
- Bread substitutions: Use any sturdy bread you like—French, sourdough, Italian, challah, or even leftover dinner rolls. Avoid very soft sandwich bread, which can become mushy.
- Cheese options: Swap cheddar for Swiss, mozzarella, pepper jack, or your favorite melting cheese. A blend of two or three cheeses adds extra flavor.
- Vegetarian version: Omit the sausage or substitute with a plant-based sausage or sautéed mushrooms for a meatless option.
- Don’t skip the soak: Allowing the casserole to rest in the fridge overnight ensures the bread fully absorbs the egg mixture, resulting in a creamy, cohesive texture. If you rush this step, the casserole may bake up dry or uneven.
Serving Suggestions
This breakfast casserole pairs beautifully with a simple side salad of mixed greens, fresh fruit, or sliced tomatoes for a balanced brunch. For a heartier spread, serve with crispy bacon, breakfast potatoes, or a bowl of yogurt and granola. A drizzle of hot sauce or a sprinkle of chopped fresh herbs like chives or parsley adds a bright finishing touch. Coffee, tea, or fresh orange juice are classic beverage choices to round out the meal.
Variations
- Southwestern twist: Add 1/2 cup drained canned green chiles, swap cheddar for pepper jack, and top with salsa and avocado before serving.
- Ham and spinach: Replace sausage with 1 1/2 cups diced cooked ham and add 2 cups fresh baby spinach (sautéed briefly to wilt) for a lighter, veggie-forward version.
- Make it dairy-free: Use your favorite plant-based milk and cheese alternatives. Note that texture and flavor will vary slightly.
- Mushroom and Gruyère: Sauté 8 ounces of sliced mushrooms with the onions and peppers, and use Gruyère or Swiss cheese for a savory, upscale twist.
- Gluten-free: Substitute your favorite gluten-free bread. Check that your sausage and cheese are gluten-free as well.
Storage and Reheating
Leftover breakfast casserole should be cooled completely, then covered or transferred to an airtight container and refrigerated within 2 hours of baking. It will keep safely in the refrigerator for up to 4 days.
To reheat individual portions, microwave on high for 1-2 minutes until hot throughout. For larger portions or the whole casserole, cover with foil and bake in a 350°F (175°C) oven for 15-20 minutes, or until heated through to an internal temperature of 165°F (74°C) per USDA food safety guidelines.
This casserole also freezes well. Wrap tightly in plastic wrap and foil, or use a freezer-safe container. Freeze for up to 2 months. To reheat, thaw overnight in the refrigerator, then bake covered at 350°F (175°C) for 25-30 minutes, or until hot in the center.
Frequently Asked Questions
- Can I assemble the casserole more than one day in advance?
- For best results, assemble the casserole no more than 24 hours before baking. Longer refrigeration can cause the bread to become overly soggy and the eggs to separate, leading to a less appealing texture. If you need to prepare ingredients further ahead, you can pre-cook the sausage and chop vegetables up to 2 days in advance, then assemble the night before baking.
- What is the best bread to use for breakfast casserole?
- Sturdy, slightly stale bread is ideal, such as French, sourdough, or Italian. These absorb the egg mixture without falling apart. Avoid soft sandwich bread, which can become mushy. If your bread is very fresh, dry it out in the oven before assembling the casserole.
- Can I use milk alternatives?
- Yes, unsweetened almond milk, soy milk, or oat milk can be used in place of whole milk. Choose an unflavored, unsweetened variety for best results. The casserole may be slightly less rich but will still set and bake well.
- How do I know when the casserole is fully cooked?
- The casserole is done when the center is set and no longer jiggles when gently shaken. You can insert a knife or toothpick into the center; if it comes out clean, it’s ready. For extra assurance, use an instant-read thermometer to check that the center has reached at least 165°F (74°C).
- Can I add more vegetables or other mix-ins?
- Absolutely! Spinach, mushrooms, zucchini, tomatoes, or even cooked potatoes can be added. Make sure to sauté or drain watery vegetables before adding to avoid excess moisture. You can also stir in cooked bacon, diced ham, or different cheeses to suit your taste.
- Why does my casserole turn out watery?
- Excess moisture can result from using very fresh bread, not draining cooked vegetables, or adding too much milk. To prevent this, use day-old bread, sauté and drain veggies, and stick to the recommended liquid ratios. Letting the casserole rest after baking also helps it firm up before slicing.