Cheesy Bagel Breakfast Casserole with Kielbasa (Overnight Recipe)

This bagel breakfast casserole with smoky kielbasa is rich, cheesy, and loaded with flavor. I like that it waits overnight in the fridge and bakes up into a big breakfast without any scrambling around.

Bagel Breakfast Casserole with Kielbasa

Bagels don’t necessarily tiptoe into breakfast, they take over. They soak up the eggs, cream, and broth in this overnight breakfast casserole like they’ve been waiting for this role, and honestly, they nail it. The kielbasa barges in with that smoky punch I’ll never stop chasing, and sharp cheddar locks it all down, bubbling over the top until the whole thing feels like it’s showing off. When I pull this bagel breakfast casserole from the oven, suddenly feeding people looks effortless.

And let me just note my own love affair with kielbasa started young. I was that kid tearing into sandwiches piled high with smoky slices (yes, weirdo), yellow mustard dripping, crusty bakery rolls from this bakery in downtown Los Angeles cracking and shattering with every bite. Totally ruined me in the best way. Ever since, I chase the kielbasa-bread duo, so of course it had to end up baked into this cheesy breakfast casserole. It’s a craveworthy meal for me.

Why I Love This Recipe

• The bagels don’t get soggy like regular bread in a breakfast casserole.
• Cheese pulls in this cheesy breakfast casserole are worth bragging about.
• Works for breakfast, lunch, or a midnight raid.
• My forever bread-meets-meat story with kielbasa.

Ingredients

A few essentials that turn a pile of bagels and eggs into something craveworthy.

• Onion bagels — chewy and sturdy.
• Kielbasa — smoky and bold.
• Mushrooms — earthy and savory.
• Shallot — mellow bite.
• Eggs — the base of it all.
• Heavy cream and whole milk — for richness.
• Beef broth — keeps things flavorful.
• Spicy brown mustard — sharp kick.
• Green onions — fresh finish.
• Salt and coarse black pepper — the basics.
• Extra-sharp cheddar — melty and indulgent.

How to Make This Bagel Breakfast Casserole

Find the complete printable recipe with measurements in the recipe card at the BOTTOM OF THE POST.

• Step One (dry out the bagels)
  Bagel cubes need to be stale or they’ll collapse in the custard. I spread mine on a baking sheet for a full day, but if time is tight a quick 15 to 20 minutes in a 350°F (175°C) oven gets the job done.
• Step Two (get the dish ready)
  Heat the oven to 375°F (190°C) and coat a 9×13-inch (23×33 cm) baking dish with nonstick spray.
• Step Three (brown the kielbasa)
  Slice the kielbasa and let it sizzle in a nonstick pan until the edges crisp and the smoky aroma starts filling the kitchen. Pull it onto a paper towel lined plate to hold. This is where the sausage breakfast casserole side of things comes alive.
• Step Four (cook the veggies)
  Add a little oil to the pan before tossing in the mushrooms. Let them cook down until the liquid is gone. Stir in the shallot and give it another minute or two until softened, then take the pan off the heat.
• Step Five (make the custard)
  In a big bowl, whisk the eggs, cream, milk, broth, mustard, green onion, salt, and pepper. Think of it like the heart of any good egg casserole.
• Step Six (build the casserole)
  Add the bagel cubes and stir until they’re soaked. Fold in the kielbasa, the mushroom-shallot mix, and half the cheese. Spread it into the prepared dish, cover, and tuck it in the fridge overnight. This is the make-ahead breakfast casserole moment that makes mornings easy.
• Step Seven (bake and finish)
  When you’re ready, uncover and scatter the rest of the cheese on top. Bake for 45 to 60 minutes, until an instant-read thermometer in the center reads 160°F (71°C). What comes out is a true cheesy breakfast casserole. Let it rest for 20 minutes before serving.

Recipe Tips

Little moves that make this casserole shine.

• This is a make-ahead breakfast casserole through and through. Letting it sit overnight is what gives the bagels time to drink up all that custard.
• If you’re more egg-forward, think of this as part egg casserole too. Nothing wrong with sneaking in an extra yolk if that’s your thing.
• Cheese matters. Extra-sharp cheddar makes this a true cheesy breakfast casserole, but mixing in a little mozzarella or gouda never hurt.
• Try this: kielbasa is my favorite, but any smoked sausage will carry this sausage breakfast casserole just fine.
• Don’t skip the rest after baking. It sets the whole thing so you can slice neat squares instead of scooping a mess.

Storing and Serving This Bagel Breakfast Casserole

Here’s how I handle leftovers and keep this breakfast casserole tasting good.

• Leftovers: Keep covered in the fridge for 3 to 4 days. I usually move slices into airtight containers.
• Reheating: Quick zap in the microwave works, but I like slipping it into a 325°F (165°C) oven until warmed through.
• Freezing: Wrap cooled slices in plastic and tuck them into freezer bags. They’ll keep for about 2 months. Thaw in the fridge overnight before reheating.
• Serving: When it comes to what to serve with breakfast casserole, I keep it simple with a honey lime fruit salad or crispy breakfast potatoes, or even a green salad if it’s lunch.

FAQs

• Can I use a different sausage instead of kielbasa?
  Yes. This is still a sausage breakfast casserole if you go with smoked sausage, chorizo, or even a milder link. Kielbasa just gives that smoky edge I like.
• Do I have to make it ahead?
  You’ll get the best results as a make-ahead breakfast casserole. The bagels need time to soak up the custard, which is why I always let it sit overnight.
• Can I add more veggies?
  Go for it. Bell peppers, spinach, or even zucchini can slip into this egg casserole without throwing anything off.
• Can this feed a crowd?
  Absolutely. It’s an easy breakfast casserole for a crowd since you can double the recipe and bake it in two dishes.
• What’s the best way to serve it?
  I treat it like a cheesy breakfast casserole centerpiece. Slice it into squares and pair it with fruit, potatoes, or something light on the side.
• Can I prep this for the holidays?
  Yes. This overnight breakfast casserole is perfect for holidays, brunches, or any morning when you want to take it easy.

More Breakfast Casseroles to Try

Once you’ve baked this bagel breakfast casserole, you’ll see how many directions a make-ahead dish can go. Here are some of my other favorites, both sweet and savory:

• Blueberry Cinnamon Roll Casserole — refrigerated cinnamon rolls, blueberries, cinnamon.
• Cinnamon Roll Casserole — refrigerated cinnamon rolls.
• Monte Cristo Casserole — buttery, cheesy, sweet and savory.
• Overnight Breakfast Casserole — biscuits, bacon, sausage, tots.
• Overnight Panettone Eggnog French Toast Casserole — spiced and perfect.
• Blueberry French Toast Casserole — sweet, eggy bread with blueberries.
• Cheesy Pepperoni Strata — rustic bread, pepperoni, spinach, cheddar.
• Overnight Apple Pie French Toast Bake — soakable bread and apple pie filling.

Finishing Off This Bagel Breakfast Casserole

Bagels crash the party, soaking up every bit of custard and holding steady under a blanket of sharp cheddar. Kielbasa barges in smoky and bold, the way it always does, and suddenly this make-ahead breakfast casserole is rich, cheesy, and exactly the kind of bread-and-sausage craving I’ve been chasing since I was a kid.

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Print Recipe

5 from 5 votes

Bagel Breakfast Casserole with Kielbasa

Bagels, smoky kielbasa, and sharp cheddar bake into one rich, cheesy overnight breakfast casserole that’s easy to make ahead and perfect for feeding a crowd.

Prep Time25 minutes mins

Cook Time1 hour hr

Overnight Chill and Resting:8 hours hrs 20 minutes mins

Total Time9 hours hrs 45 minutes mins

Course: Breakfast, Brunch

Cuisine: American

Keyword: bagel breakfast casserole, cheesy breakfast casserole, easy breakfast casserole for a crowd, egg casserole, Make Ahead Breakfast casserole, Overnight Breakfast Casserole, Overnight Egg Casserole, sausage breakfast casserole, what to serve with breakfast casserole

Servings: 12

Calories: 414kcal

Author: Cathy Pollak

Equipment

• baking dish 9x13 (23x33). Roomy enough for all the layers.
• nonstick skillet Browns the kielbasa and cooks the veggies.
• mixing bowls To whisk the custard.
• whisk For beating eggs and cream together.

Ingredients

• 1 lb (454 g) onion bagels cubed
• cooking spray
• 14 oz (397 g) kielbasa halved lengthwise and sliced
• 1 tbsp (15 ml) vegetable oil
• 10 oz (283 g) sliced mushrooms
• 1 large shallot finely minced
• 10 large eggs
• 1 cup (240 ml) heavy cream
• ½ cup (120 ml) whole milk
• ½ cup (120 ml) low-sodium beef broth
• ½ cup (120 g) spicy brown mustard
• ¼ cup (25 g) sliced green onions
• 1 tsp (6 g) table salt
• 1 tsp coarsley ground black pepper
• 8 oz (227 g) shredded extra-sharp cheddar cheese divided

Instructions

• Place the bagel cubes on a baking sheet and let them stale overnight until completely dry, about 24 hours. Alternatively, bake them in a 350°F (175°C) oven for 15 to 20 minutes.
  1 lb (454 g) onion bagels
• Preheat the oven to 375°F (190°C) and coat a 9×13-inch (23×33 cm) baking dish with nonstick spray.
  cooking spray
• In a nonstick pan over medium heat, brown the kielbasa until the edges are crisp. Remove with a slotted spoon onto a paper towel lined plate.
  14 oz (397 g) kielbasa
• Add the oil to the same pan, then stir in the mushrooms and cook until they release their liquid and it evaporates. Stir in the shallot and cook until softened, 1 to 2 minutes. Remove from the heat.
  1 tbsp (15 ml) vegetable oil, 10 oz (283 g) sliced mushrooms, 1 large shallot
• In a large bowl, whisk together the eggs, cream, milk, broth, mustard, green onion, salt, and pepper.
  10 large eggs, 1 cup (240 ml) heavy cream, ½ cup (120 ml) whole milk, ½ cup (120 ml) low-sodium beef broth, ½ cup (120 g) spicy brown mustard, ¼ cup (25 g) sliced green onions, 1 tsp (6 g) table salt, 1 tsp coarsley ground black pepper
• Add the bagel cubes to the bowl and toss to coat in the mixture.
• Fold in the kielbasa, mushroom-shallot mixture, and half of the cheese. Transfer everything to the prepared baking dish, cover, and refrigerate overnight.
  8 oz (227 g) shredded extra-sharp cheddar cheese
• When ready to bake, sprinkle the remaining cheese over the top. Bake for 45 to 60 minutes, or until an instant-read thermometer inserted in the center registers 160°F (71°C).
• Let the casserole rest for 20 minutes before serving.

Notes

• Bagels make this sturdier than most breakfast casseroles, with a chewy bite that doesn’t go soggy.
• For a true cheesy breakfast casserole, mix cheddar with gouda or mozzarella.
• Kielbasa is classic here, but any smoked sausage works in this sausage breakfast casserole.
• This is the kind of make-ahead breakfast casserole that shines on weekends or holidays.
• Bell peppers, spinach, or zucchini can be folded in if you like more of an egg casserole feel.

 

If you’re making this bagel breakfast casserole, check out the full post. That’s where I keep extra tips, FAQs, and details that don’t always make it into the recipe card.

Nutrition info is an estimate and will vary depending on the brands you use.

©Noble Pig. All content and photos are copyright protected. Sharing the recipe link is always appreciated, but copying and pasting the full recipe anywhere else isn’t allowed.

Nutrition

Nutrition Facts

Bagel Breakfast Casserole with Kielbasa

Amount Per Serving (220 g)

Calories 414 Calories from Fat 270

% Daily Value*

Fat 30g46%

Saturated Fat 14g88%

Polyunsaturated Fat 3g

Monounsaturated Fat 10g

Cholesterol 216mg72%

Sodium 875mg38%

Potassium 274mg8%

Carbohydrates 23g8%

Fiber 1g4%

Sugar 3g3%

Protein 17g34%

Vitamin A 825IU17%

Vitamin C 1mg1%

Calcium 200mg20%

Iron 2mg11%

* Percent Daily Values are based on a 2000 calorie diet.

Have you made this Bagel Breakfast Casserole? I’d love to hear how it turned out — leave a comment below and let me know.

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