Introduction

This Overnight Breakfast Sausage Casserole is the kind of recipe that makes mornings feel easy—especially when you’re feeding a group. It’s a classic make-ahead egg bake built from simple ingredients: browned sausage, eggs, milk, cubes of toasted bread, and plenty of cheddar. Everything gets mixed together, poured into a baking dish, and chilled overnight so the bread can soak up the custardy egg mixture. The next day, you bake it until golden and set, and breakfast is basically done.

The flavor is rich and savory, with a gentle tang from cheddar and a warm, slightly “breakfasty” note from mustard powder (it doesn’t taste like mustard—more like it rounds out the sausage and cheese). The bread gives the casserole a soft, soufflé-like interior with crisp edges on top. It’s perfect for weekend brunch, holiday mornings, meal prep breakfasts, or any time you want a satisfying dish that can be assembled ahead and baked when you’re ready.

Why You’ll Love This Recipe

• Make-ahead magic: Assemble the night before, then bake in the morning.

• Perfect for a crowd: Easy to slice into portions and serve buffet-style.

• Comforting and filling: Sausage + eggs + cheese = hearty breakfast energy.

• Flexible: Swap bread types, cheese, or add vegetables to match your taste.

Equipment

• 9×13-inch baking dish

• Large skillet

• Mixing bowl

• Whisk

• Measuring cups and spoons

• Spatula or wooden spoon

• Foil

• Instant-read thermometer (optional but helpful)

Ingredients

Main Ingredients

• 1 lb bulk pork sausage

• 4 large eggs, beaten

• 2 cups milk

• 1 tsp mustard powder

• 1/4 tsp salt

• 6 slices Italian or sourdough bread, toasted and cut into cubes

• 2 cups shredded mild or sharp cheddar cheese (about 8 oz)

Optional Ingredients

• Black pepper (sausage often has pepper already, but you can add more)

• Chopped green onions (fresh finish)

• Diced bell pepper or sautéed onion (adds sweetness and texture)

• Hot sauce for serving

• Extra cheese on top for a more browned finish

Instructions

Step 1: Preparation

1. Grease a 9×13-inch baking dish.

2. Toast the bread slices until lightly crisp, then cut into cubes.
   Toasting helps the bread hold its texture during the overnight soak.

Step 2: Mixing / Assembling

1. In a large skillet over medium heat, cook the sausage, breaking it into small pieces, until browned—about 5 minutes.

2. Drain excess fat and set sausage aside.

3. In a large bowl, whisk together the beaten eggs, milk, mustard powder, and salt until smooth.

4. Add the cooked sausage, bread cubes, and shredded cheddar to the bowl. Stir until everything is evenly coated.

5. Pour the mixture into the prepared baking dish and spread it out evenly.

Step 3: Chilling / Resting

1. Cover the dish with foil.

2. Refrigerate overnight (or at least 6–8 hours).
   This step allows the bread to absorb the egg mixture, creating a tender, custardy bake.

Step 4: Baking

1. Preheat oven to 350°F (175°C).

2. Bake covered for 45 minutes.

3. Reduce the oven temperature to 325°F (163°C).

4. Remove foil and bake uncovered until the center is set and reaches 165°F (74°C), about 15 minutes more.

5. Let rest 10 minutes before slicing so it firms up for cleaner portions.

Tips & Notes

• Best texture tip: Toast the bread and chill overnight—this prevents sogginess and gives the casserole a better set.

• Flavor enhancement: Mustard powder deepens the savory flavor without tasting like mustard. It’s subtle but noticeable in a good way.

• Common mistake to avoid: Baking too hot at the end can dry it out. Lowering the oven to 325°F helps it finish gently.

• Portion tip: Use a sharp knife and let it rest before cutting for neat squares.

Variations

Ingredient Variations

• Veggie add-in: Add sautéed mushrooms, spinach (squeezed dry), or diced peppers.

• Spicy version: Use hot breakfast sausage or add crushed red pepper.

• Cheese swap: Try pepper jack, Colby, Swiss, or a cheddar blend.

Dietary Variations

• Gluten-free: Use gluten-free bread (toast it well).

• Lower fat (modified): Use turkey breakfast sausage and 2% milk (texture slightly lighter).

• Dairy-free (modified): Use unsweetened non-dairy milk and dairy-free cheddar-style shreds (set may be softer).

Storage & Make-Ahead

• Refrigerator: Store leftovers for up to 4 days.

• Freezer: Freeze slices individually for up to 2 months.

• Make-ahead tip: This casserole is already make-ahead. You can also cook the sausage and cube the bread the day before to speed things up.

Serving Suggestions

• Fresh sides: Fruit salad, berries, or sliced oranges.

• Brunch extras: Hash browns, roasted potatoes, or a simple green salad.

• Sauces: Hot sauce, salsa, or a spoon of sour cream on top.

Time Breakdown

• Preparation Time: 25 minutes

• Cooking Time: 60 minutes (baking)

• Chilling Time: 8 hours (overnight)

• Total Time: 9 hours 25 minutes

• Servings: 8

Nutritional Information (Per Serving)

• Calories: 384

• Protein: 22 g

• Carbohydrates: 15 g

• Fat: 24 g

• Sodium: 773 mg

Frequently Asked Questions

Can I use leftovers or substitutions?

Yes. Use any sturdy bread (French bread works great). You can swap cheddar for another melty cheese. If your sausage is strongly seasoned, you may want to reduce added salt slightly and taste after baking.

Can I make this recipe ahead of time?

That’s the best part—assemble the night before and bake in the morning. You can also bake it fully, cool, and reheat the next day for an even easier breakfast.

How do I reheat it properly?

• Oven: 325°F, covered with foil, until warmed through.

• Microwave: Heat individual slices in short bursts to avoid rubbery eggs.

Can I freeze this recipe?

Yes. Freeze baked slices individually. Thaw overnight in the fridge or reheat from frozen in the oven (covered) until hot.

Conclusion

This Overnight Breakfast Sausage Casserole is a reliable, comforting make-ahead breakfast that saves you time when it matters most. It’s hearty, cheesy, and satisfying—perfect for family mornings, holiday brunch, or meal prep slices you can reheat all week.