Overnight Breakfast Casserole

If you love waking up to a warm, hearty breakfast without doing the work in the morning, this Overnight Breakfast Casserole is your new go-to recipe. Packed with fluffy eggs, melty cheese, veggies, and savory beef or chicken sausage, it’s perfect for holidays, brunch parties, or busy weekday mornings. Just prep it the night before, refrigerate, and bake it fresh when you wake up!

Want recipes like this delivered straight to your inbox? Subscribe now to get the latest culinary creations you’ll love.

Why You’ll Love This Recipe
Make-Ahead Friendly – Prep at night and bake in the morning.
Customizable – Add your favorite vegetables, proteins, or cheeses.
Perfect for Feeding a Crowd – Ideal for holidays and gatherings.
Comforting & Satisfying – A complete meal in one dish.
Kid-Approved – Mild, cheesy, and full of familiar breakfast flavors.

Ingredients You’ll Need

For the Casserole Base:

• 6 large eggs
• 2 cups milk (any kind)
• 1 tsp Dijon mustard (optional, for depth of flavor)
• ½ tsp salt
• ½ tsp black pepper
• ½ tsp garlic powder
• ½ tsp onion powder

For the Filling:

• 4 cups cubed bread (day-old works best – French, sourdough, or whole grain)
• 1 cup shredded cheddar or mozzarella cheese
• ½ lb ground beef or chicken sausage, cooked and crumbled
• ½ cup chopped red bell pepper
• ½ cup chopped onion
• 1 cup baby spinach or kale, chopped
• 2 tbsp fresh parsley, chopped (for garnish)

Optional Add-ins:

• ¼ cup sun-dried tomatoes
• ½ cup mushrooms, sautéed
• A pinch of red pepper flakes for a spicy version

Tools You’ll Need

• 9×13-inch baking dish
• Skillet
• Mixing bowls
• Whisk
• Measuring cups and spoons
• Plastic wrap or foil
• Spatula

Step-by-Step Instructions

Step 1: Prepare the Filling

1. In a skillet over medium heat, cook ground beef or chicken sausage until browned and cooked through. Drain any excess fat.
2. Sauté the chopped onion and bell pepper in the same skillet for 3–4 minutes until slightly softened.
3. Add spinach or kale and cook just until wilted. Set aside to cool.

Step 2: Assemble the Casserole
4. Lightly grease a 9×13-inch baking dish.
5. Spread the cubed bread evenly in the dish.
6. Top with the cooked meat and vegetable mixture.
7. Sprinkle shredded cheese evenly on top.

Step 3: Whisk the Egg Mixture
8. In a large mixing bowl, whisk together eggs, milk, Dijon mustard, salt, pepper, garlic powder, and onion powder.
9. Pour the egg mixture over the casserole, pressing down gently so the bread absorbs the liquid.

Step 4: Refrigerate Overnight
10. Cover the casserole tightly with plastic wrap or foil.
11. Refrigerate for at least 6 hours or overnight to allow the flavors to meld and the bread to soak up the custard.

Step 5: Bake and Serve
12. Preheat oven to 350°F (175°C).
13. Remove casserole from the refrigerator and let sit at room temperature for 20 minutes.
14. Bake uncovered for 45–50 minutes, or until the center is set and the top is golden brown.
15. Let cool for 5–10 minutes, then garnish with fresh parsley and slice to serve.

Tips for Success
Use Day-Old Bread – It holds up better and soaks in the egg mixture without getting soggy.
Let It Rest – A brief cooling period after baking helps everything set and slice neatly.
Adjust for Dietary Needs – Use dairy-free milk, meat alternatives, or gluten-free bread.
Make It Cheesy – Add extra cheese between layers for maximum flavor.
Double the Recipe – For a large crowd, double ingredients and bake in two pans.

Serving Suggestions
Holiday Brunch – Pair with fruit salad, muffins, or cinnamon rolls.
Everyday Breakfast – Serve with yogurt and fresh berries.
Quick Reheat – Warm up leftovers for a fast weekday breakfast.
Add Hot Sauce – A splash of sriracha or salsa adds a spicy kick.

How to Store & Reheat

Storing:

• Refrigerate: Store leftovers in an airtight container for up to 4 days.
• Freeze: Wrap individual slices or the full casserole tightly and freeze for up to 2 months.

Reheating:

• Oven: Reheat covered at 325°F for 15–20 minutes until warmed through.
• Microwave: Warm individual slices in 30-second intervals until hot.

Frequently Asked Questions

1. Can I make this vegetarian?
   Yes! Skip the meat or replace it with plant-based sausage or extra veggies like mushrooms and zucchini.
2. What’s the best bread to use?
   French bread, sourdough, or any hearty loaf. Avoid soft sandwich bread—it tends to get mushy.
3. Can I bake it right away?
   Yes, just allow the bread to soak for at least 30 minutes before baking.
4. How do I know it’s done?
   The center should be set and not jiggly. Insert a knife—it should come out clean.

Final Thoughts
This Overnight Breakfast Casserole brings all the flavors of your favorite morning meal into one cozy, baked dish. It’s easy to prep, delicious to eat, and endlessly adaptable. Whether you’re planning a holiday brunch or prepping for a busy week, this recipe will become a go-to favorite.

Try it out and share your version! I’d love to see your creative twists on this classic dish.

Preparation Time: 15 minutes
Cooking Time: 50 minutes
Chill Time: 6–12 hours
Cuisine: American

Nutritional Information (Per Serving):
Calories: 320 | Protein: 18g | Carbohydrates: 22g | Fat: 18g | Fiber: 2g | Sodium: 450mg

Print