Overnight Sausage and Egg Breakfast Casserole

Looking for an absolutely dreamy breakfast that basically cooks itself? You need this Overnight Sausage and Egg Breakfast Casserole in your life! It's rich, fluffy, and loaded with hearty sausage, melty cheese, and golden, custardy bread cubes.

The best part? You prep everything the night before, let it soak up all that amazing flavor, and just pop it in the oven in the morning. No fuss, no flipping pancakes, just a warm, crowd-pleasing casserole that makes your kitchen smell incredible.

This is my go-to for holiday mornings, lazy weekends, or anytime I want to start the day with something cozy and comforting. It’s perfect for feeding a group or meal prepping breakfast for the week!

Why You'll Love This Recipe

• Stress-free mornings: Prep it the night before for effortless, hands-off breakfast magic.
• Feeds a crowd: Hearty, satisfying, and perfect for brunch gatherings or holidays.
• Ultimate comfort food: Savory sausage, fluffy eggs, and gooey cheese in every bite.
• Customizable: Easily swap in your favorite cheeses, veggies, or breads to make it your own.

Key Ingredients for Overnight Sausage and Egg Breakfast Casserole

See recipe card below for full list of measurements, ingredients, and instructions.

Breakfast Sausage

Sausage is the savory star of this casserole, infusing every bite with rich, seasoned flavor. Use your favorite brand of bulk breakfast sausage (pork or turkey both work). You can go for spicy or mild, depending on your taste. Brown it well for extra depth, and be sure to drain excess fat for the best texture. Vegetarian? Use a plant-based sausage instead!

Eggs

Eggs create the luscious, custardy base that binds everything together. Use large eggs for the most reliable results. Whisk them thoroughly with milk and seasonings to ensure a smooth, evenly distributed mixture. If you like, you could substitute half the eggs with liquid egg whites for a lighter version.

Bread

Cubed bread soaks up all the eggy goodness, turning wonderfully golden and soft as it bakes. Day-old or slightly stale bread works best, as it holds its shape and gives the casserole structure. Any hearty white bread, French bread, or even sourdough will do—just avoid breads that are too soft or sweet.

Cheese

Shredded cheese adds gooey, melty richness and flavor throughout the casserole. I love using sharp cheddar for its bold taste, but Swiss, Monterey Jack, or a blend will work beautifully. For a little kick, try pepper jack or add a sprinkle of Parmesan on top.

Milk

Milk is essential for creating the creamy custard that soaks into the bread and eggs. Whole milk gives the richest result, but 2 percent works well too. For a dairy-free option, unsweetened almond or oat milk can be substituted—just expect a slightly different texture.

Instructions for Overnight Sausage and Egg Breakfast Casserole

See recipe card below for full list of measurements, ingredients, and instructions.

Brown the Sausage

Start by heating a large skillet over medium heat. Add the sausage, breaking it up with a spoon as it cooks. Sauté until browned and fully cooked, about 6 to 8 minutes. Drain any excess fat and set the sausage aside to cool slightly.

Prepare the Bread

While the sausage cooks, cut your bread into 1-inch cubes. Arrange the cubes evenly in a well-greased 9x13-inch baking dish. Make sure the bread forms a nice, even layer—this helps the custard soak in perfectly.

Layer the Casserole

Sprinkle the cooked sausage evenly over the bread cubes. Add 1 1/2 cups of the shredded cheese, then scatter green onions over the top if you're using them.

Mix the Egg Custard

In a large bowl, whisk together the eggs, milk, salt, pepper, garlic powder, and dried mustard (if using). Whisk until everything is fully combined and the eggs are frothy—this makes the casserole extra fluffy!

Pour and Chill

Gently pour the egg mixture over the bread, sausage, and cheese. Press down lightly with the back of a spoon to help the bread absorb the custard. Cover tightly with plastic wrap or foil and refrigerate overnight (at least 8 hours, or up to 24).

Bake Until Golden

When you're ready to bake, preheat your oven to 350°F (175°C). Remove the casserole from the fridge and let it sit at room temperature for about 20 minutes while the oven heats. Sprinkle the remaining 1/2 cup of cheese over the top. Bake uncovered for 45 to 55 minutes, or until the casserole is puffed, golden, and a knife inserted in the center comes out clean. If the top is browning too quickly, loosely tent with foil.

Rest and Serve

Let the casserole cool for 10 minutes before slicing. This helps it set up and makes serving easier. Garnish with extra green onions or fresh herbs if you like, and enjoy!

Recipe Variations

Veggie Lover’s Option

Want to pack in some extra veggies? Add sautéed mushrooms, bell peppers, spinach, or broccoli along with the sausage for delicious color and nutrition. Just make sure veggies are cooked and well-drained so the casserole doesn't get watery.

Gluten-Free Adaptation

Use your favorite gluten-free bread in place of regular bread. Day-old or lightly toasted gluten-free bread works best to soak up the custard without getting mushy.

Dairy-Free Makeover

Swap the milk for unsweetened almond, soy, or oat milk, and use a dairy-free shredded cheese. The casserole still bakes up creamy and satisfying!

Spice It Up

Like a little heat? Go for spicy breakfast sausage or add a pinch of crushed red pepper flakes to the egg mixture. You can also tuck in some diced jalapeños for a real wake-up call.

Meat-Free Version

Replace the sausage with a plant-based sausage crumbles or a mix of sautéed mushrooms and onions for a hearty, vegetarian spin.

Serving Suggestions

This casserole is a complete breakfast on its own, but it pairs beautifully with fresh fruit salad, crispy hash browns, or a simple green salad for brunch. Garnish with chopped herbs, extra green onions, or a dollop of salsa for a flavor boost. For a sweet touch, serve with a side of maple syrup or jam.

Storage and Reheating

Leftover casserole keeps well! Store cooled slices in an airtight container in the refrigerator for up to 4 days. Reheat individual portions in the microwave for 1-2 minutes or in a 350°F oven for about 15 minutes until warmed through. The casserole can also be frozen, tightly wrapped, for up to 2 months. Thaw overnight in the fridge before reheating.

Frequently Asked Questions About Overnight Sausage and Egg Breakfast Casserole (FAQ)

Q: Can I assemble the casserole more than one day in advance?
A: Yes! You can prepare the casserole up to 24 hours ahead. Longer than that, the bread can get too soggy, so plan to bake within a day for best texture.

Q: What kind of bread works best for this casserole?
A: Use sturdy, day-old bread like French bread, sourdough, or a hearty white loaf. Avoid very soft sandwich bread, which can get mushy.

Q: Can I make this recipe without sausage?
A: Absolutely! Omit the sausage or replace it with a vegetarian or turkey alternative, or load up on sautéed veggies for a meat-free version.

This Overnight Sausage and Egg Breakfast Casserole is the easiest, most comforting way to feed a crowd—and guarantee a cozy start to any day! If you try this recipe, I'd love to hear how it turned out. Leave a rating or comment below and share your favorite spins!