Breakfast casserole with bread is the kind of dish that solves busy mornings. It’s assembled the night before so all you have to do is slide it into the oven while coffee brews.

Layers of custard-soaked bread, savory sausage, peppers, and melted cheese bake into a golden, puffy casserole that feeds a crowd. Serve it with a simple fruit salad and you’re done.

Why This Casserole Saves the Morning

I keep coming back to this breakfast casserole because it does the heavy lifting before anyone’s awake. The bread soaks up the egg mixture overnight, turning soft and almost bread-pudding-like inside with crisp edges.

It’s forgiving, too. Swap in whatever cheese or breakfast meat you have on hand, and it still comes out rich and satisfying. The hallmark is a custardy center that holds together when you slice it.

Ingredients

8 oz (about 6 cups) cubed day-old bread: sourdough, French, or brioche all work well
1 lb (450g) chicken breakfast sausage: casings removed if using links
1 medium onion, diced
1 bell pepper, diced: any color, green or red adds nice contrast
8 large eggs
2 cups (480ml) whole milk
1 tsp dry mustard powder
1 tsp kosher salt
½ tsp black pepper
2 cups (8 oz/225g) shredded sharp cheddar cheese, divided
2 Tbsp sliced fresh chives, for garnish

Variations / Substitutions

Meat: crumbled cooked bacon, cubed ham, or a plant-based sausage work instead of chicken sausage.
Vegetarian: omit the sausage and add 1 cup sautéed mushrooms plus a handful of spinach.
Bread: stale challah or a sturdy gluten-free loaf can replace the bread; avoid soft sandwich bread.
Cheese: pepper jack, smoked gouda, or mozzarella all melt beautifully.
Dairy-free: use unsweetened almond milk and a dairy-free shredded cheese alternative. The custard will be less rich but still set.

For a handheld version, try our Sausage and Egg Breakfast Burritos.

How to Make Overnight Breakfast Casserole with Bread

Step 1: Brown the Sausage and Vegetables

Heat a large skillet over medium-high heat. Add the 1 lb sausage and cook, breaking it up with a spoon, until no longer pink, about 8 minutes. Stir in the diced onion and bell pepper and cook, stirring occasionally, until the vegetables soften, 5 minutes more. Drain off any excess fat and set the mixture aside to cool slightly.

The sausage should be crumbled and deeply browned in spots. The peppers and onions will look glossy and just tender, without being fully limp. Cooling the mixture for a few minutes keeps it from scrambling the eggs later.

Step 2: Soak the Bread and Custard

In a large bowl, whisk together the 8 eggs, 2 cups milk, 1 tsp mustard powder, 1 tsp salt, and ½ tsp pepper until smooth. Add the bread cubes and gently fold them into the custard until every piece is coated. Let the bread soak for at least 10 minutes at room temperature, or cover and refrigerate overnight for the best texture.

The bread will look completely sodden, which is exactly what you want. It should be heavy with liquid and starting to break down a bit at the edges. If you’re making it the night before, just pop the bowl in the fridge and stir once before assembling.

Step 3: Assemble the Casserole

Grease a 9×13-inch (3-quart) baking dish. Spread half of the soaked bread mixture evenly across the bottom. Scatter the sausage and vegetable mixture over it, then sprinkle with 1 cup of the shredded cheddar. Top with the remaining soaked bread, spreading it out to cover the filling. Pour any leftover custard from the bowl over the top and finish with the remaining 1 cup of cheese.

Press down gently with a spatula or your fingers so the top layer nestles into the liquids. This helps the custard rise evenly through the casserole as it bakes. At this point, you can cover and refrigerate for up to 12 hours before baking.

Step 4: Bake and Serve

Preheat the oven to 350°F (175°C). Remove the casserole from the fridge while the oven heats if it’s been chilled overnight. Bake until the top is puffed and deeply golden and the center is set, 45 to 50 minutes. A knife inserted near the middle should come out clean.

Let the casserole rest on the counter for 5 minutes before slicing. It will settle slightly as it cools, making it easier to cut into clean squares. Sprinkle with the sliced chives and serve hot.

A Few Tips Before You Start

If your bread is very fresh, spread the cubes on a baking sheet and dry in a 300°F oven for 10 minutes before soaking. This prevents a gummy texture.
For a crispier top, sprinkle an extra handful of cheese over the casserole during the last 10 minutes of baking.
You can assemble the whole dish without baking, wrap it tightly, and freeze for up to 2 months. Bake straight from frozen, adding 20 to 25 minutes to the bake time.
Make individual portions by dividing the layers into greased ramekins. Reduce the bake time to 25 to 30 minutes.

Bake times can shift depending on your dish:

Dish Material	Bake Time at 350°F
Glass or metal 9×13 pan	45 to 50 minutes
Ceramic baking dish	50 to 55 minutes
Ramekins (individual)	25 to 30 minutes

Keeping Leftovers Fresh

Refrigerate: store cooled casserole in an airtight container for up to 4 days.
Reheating: warm individual portions in the microwave, or cover the whole dish with foil and heat in a 300°F oven until hot, about 15 minutes.
Serve cold: not ideal, but a cold slice is perfectly edible if you’re in a rush.

What to Serve With Overnight Breakfast Casserole with Bread

A simple green salad with a lemon vinaigrette cuts through the richness of the sausage and cheese. Fresh fruit or a berry compote adds a sweet, bright contrast. Roasted cherry tomatoes on the side bring a gentle acidity that balances every bite.

Frequently Asked Questions

Can I freeze this casserole?

Yes. Assemble the unbaked casserole, wrap it tightly in foil, and freeze for up to 2 months. Bake directly from frozen, adding 20 to 25 minutes to the listed bake time. Check the center reaches 160°F before pulling it out.

Why did my casserole turn out soggy?

Sogginess usually means the casserole needed more oven time. Make sure the center is fully set and the top is deeply golden. Using very fresh, soft bread without drying it first can also lead to a wet result.

Can I use egg whites only?

You can, but the casserole will be less rich and may bake up slightly more rubbery. If you want to lighten it, replace half the whole eggs with egg whites.

Is it okay to leave out the sausage for a vegetarian version?

Absolutely. Omit the sausage and add 1 cup sautéed mushrooms and a handful of spinach instead. The bake time stays the same.