Sausage, Pepper & Onion Morning Casserole – Hearty, Savory, and Perfect for Breakfast

This is the kind of breakfast that makes the whole house smell incredible. Savory sausage, sweet peppers, and onions bake together with eggs and cheese into a cozy, satisfying casserole. It’s unfussy, feeds a crowd, and works just as well for a lazy weekend as it does for meal prep.

You can prep it the night before, slide it into the oven in the morning, and let it do the work while you make coffee. Simple, flavorful, and always a hit.

What Makes This Recipe So Good

• Big flavor, minimal effort: Browning sausage with peppers and onions builds a ton of flavor fast. The oven does the rest.
• Great for feeding a group: One casserole pan serves 6–8 easily, with consistent portions and no last-minute stovetop scramble.
• Make-ahead friendly: Assemble it the night before, then bake in the morning.

  It’s a stress-free breakfast plan.

• Flexible ingredients: Use sweet or hot Italian sausage, swap cheeses, or toss in leftover veggies. It’s very forgiving.
• Hearty and satisfying: Protein-rich eggs and sausage help keep you full and focused, without being heavy or greasy.

Ingredients

• 1 pound Italian sausage (sweet or hot), casings removed
• 1 medium yellow onion, thinly sliced
• 1 red bell pepper, thinly sliced
• 1 green bell pepper, thinly sliced
• 2 cloves garlic, minced
• 8 large eggs
• 1 cup whole milk (or half-and-half for richer texture)
• 1 cup shredded mozzarella
• 1/2 cup shredded sharp cheddar
• 2 cups day-old bread cubes (Italian or sourdough), optional for a heartier casserole
• 2 tablespoons olive oil (if needed)
• 1 teaspoon kosher salt, divided
• 1/2 teaspoon black pepper
• 1/2 teaspoon smoked paprika
• 1/2 teaspoon dried oregano
• 1/4 teaspoon red pepper flakes, optional
• Fresh parsley or chives, chopped, for garnish
• Nonstick cooking spray or butter, for greasing the dish

How to Make It

1. Prep the dish: Preheat oven to 350°F (175°C). Grease a 9×13-inch baking dish with cooking spray or butter.
2. Brown the sausage: Heat a large skillet over medium-high.

   Add sausage and cook, breaking it up, until browned and cooked through, about 6–8 minutes. Transfer to a plate, leaving a little fat in the pan. If the pan is dry, add a drizzle of olive oil.

3. Cook the peppers and onions: Add onions and bell peppers to the skillet with 1/2 teaspoon salt.

   Cook, stirring often, until softened and lightly caramelized at the edges, 6–8 minutes. Stir in garlic and cook 30 seconds.

4. Season the mixture: Return sausage to the skillet. Add smoked paprika, oregano, and red pepper flakes.

   Toss to combine, then remove from heat.

5. Layer the base: If using bread, scatter the cubes evenly in the prepared baking dish. Spoon the sausage-pepper-onion mixture over the bread (or directly into the dish if skipping bread). Sprinkle mozzarella and cheddar evenly on top.
6. Whisk the custard: In a large bowl, whisk eggs, milk, remaining 1/2 teaspoon salt, and black pepper until smooth and frothy.
7. Combine and rest: Pour the egg mixture over the casserole.

   Press down lightly with a spatula so everything is moistened. Let sit 10 minutes so the bread, if using, absorbs some custard.

8. Bake: Cover with foil and bake for 20 minutes. Remove foil and bake another 18–22 minutes, until the center is set and the top is golden and puffed.

   A knife inserted in the center should come out clean.

9. Finish and serve: Let rest 10 minutes before slicing. Garnish with chopped parsley or chives. Serve warm.

Keeping It Fresh

• Refrigerate: Store leftovers in an airtight container for up to 4 days.

  Reheat covered at 325°F until warmed through, or microwave in 30-second bursts.

• Freeze: Wrap individual portions tightly and freeze up to 2 months. Thaw in the fridge overnight, then reheat in the oven for best texture.
• Make-ahead: Assemble the casserole, cover, and refrigerate up to 12 hours before baking. Add 5–10 minutes to the bake time if going from cold.
• Avoid sogginess: If using fresh bread, toast the cubes first at 300°F for 10–12 minutes to dry them out slightly.

Health Benefits

• Protein-rich: Eggs and sausage deliver solid protein to keep you full longer, which can help reduce mid-morning snacking.
• Vegetable boost: Bell peppers and onions add fiber, vitamin C, and antioxidants without weighing the dish down.
• Customizable nutrition: You can use turkey sausage, part-skim cheese, or extra veggies to lighten it up without losing flavor.
• Balanced energy: Pairing protein, fat, and optional carbs (bread) provides steady energy for busy mornings.

Common Mistakes to Avoid

• Skipping the browning step: Sausage and vegetables need time in the pan to develop flavor.

  Don’t rush this part.

• Using very fresh bread: Soft bread can turn mushy. Day-old or lightly toasted bread helps create a better texture.
• Overbaking: The casserole should be set but still tender. Overcooking can make it dry and rubbery.
• Underseasoning: Eggs need salt.

  Taste the sausage-pepper mix and season the egg custard to keep flavors balanced.

• Too much liquid from veggies: If peppers release excess moisture, cook them a bit longer to drive it off before assembling.

Alternatives

• Meat swaps: Try turkey sausage, chicken sausage, or crumbled cooked bacon. For a lighter dish, use half sausage and half mushrooms.
• Cheese options: Monterey Jack for mild creaminess, provolone for Italian vibes, or goat cheese for tangy richness.
• Veggie add-ins: Spinach, mushrooms, zucchini, or roasted tomatoes work well. Sauté watery veggies first.
• No-bread version: Skip the bread entirely for a crustless, lower-carb casserole.

  Add an extra egg for structure if needed.

• Dairy-free: Use a creamy, unsweetened plant milk and skip the cheese or use a good melting dairy-free cheese.
• Spice it up: Add chopped pickled peppers or a spoonful of Calabrian chili paste for a kick.

FAQ

Can I make this the night before?

Yes. Assemble the casserole, cover, and refrigerate overnight. Bake in the morning, adding a few extra minutes since it starts cold.

What kind of sausage works best?

Italian sausage is classic.

Use sweet for mild flavor or hot for heat. Turkey or chicken sausage also works if you prefer a leaner option.

Do I have to use bread?

No. The casserole sets nicely without it, especially if you include plenty of sausage and vegetables.

Bread just adds a heartier, strata-like texture.

How do I know when it’s done?

The center should no longer jiggle, and a knife inserted in the middle should come out clean. The top will be lightly golden and puffed.

Can I reduce the dairy?

You can use a lower-fat milk or unsweetened almond milk. The texture will be slightly less creamy but still delicious.

How can I add more veggies without making it watery?

Sauté additions like mushrooms or spinach until most of their moisture cooks off.

Then fold them into the sausage mixture before baking.

Is this good for meal prep?

Absolutely. Bake once, cool, slice into squares, and store in containers. Reheats well and keeps its texture for several days.

In Conclusion

Sausage, Pepper & Onion Morning Casserole brings comfort, flavor, and convenience together in one pan.

It’s flexible enough to adjust to your crowd and your fridge, and sturdy enough to keep you satisfied all morning. Whether you cook it for a weekend brunch or portion it for weekday breakfasts, it’s a reliable, tasty favorite you’ll make again and again. Keep the ingredients simple, season well, and enjoy the kind of breakfast that makes the day start right.